VistaLover

Actually, this is normal; you should realise that while the UXP platform was forked from a Firefox ESR 52.6.0 platform snapshot, the application Pale Moon 28 itself (built on the UXP platform) does not implement the Australis GUI, much like its previous major version 27. The feature you describe was added on top of the Australis interface (Fx >=29.0) by Mozilla developers and should be there in both Firefox ESR 52.9.0 / Basilisk 52 (Serpent 52.9.0), as long as you do not move the "Zoom Controls" button (- +) to a browser toolbar; this native browser feature was not present in the pre-Australis (Fx <=28.0) Firefox GUI that PM uses... There's nothing to fix here, as explained above; BTW, you should not expect @roytam1 to implement major new features in New Moon 28 (his fork) that are not yet present upstream, i.e. in original Pale Moon 28 source (master branch); the way I see it (and please someone correct me if I am wrong), Roy's main focus is/should be creating and testing patches to Pale Moon that will enable it to run on Windows XP + Vista, both OSs that the official app has dropped support for; main browser code is still the task for Moonchild Productions; if you do find a bug inside Roy's patches (that enable XP+Vista support), by all means report it here, but GUI improvements + implementation of new features should not, IMHO, be a thing for Roy... In any case, if you want the requested functionality in New Moon 28 (currently at version 28.2.0a1), you can install an extension which offers pretty much the same thing, Zoom Page v15.7 (it creates a button that can be placed inside any toolbar, but, sadly, not inside the URLbar): I think it's universally accepted there's no software that is bug-free; however, your bug reporting skills are very flimsy in this case; please read Information to include when asking for support ; providing just a screengrab without further info (e.g. the URL details of the page where this occurs) so other people here can test and try to reproduce results in pure sensationalism, with slim chances of a resolution of your issue... Please understand I have nothing personal against you , my advice above was simply offered so us members here can help each other in a more productive manner... Regards

Not that it comes as a surprise, but following Bugzilla bug (#1495991) labelled WONTFIX : https://bugzilla.mozilla.org/show_bug.cgi?id=1495991 (Reconsider extending security support for Firefox 52ESR on Windows XP and Vista)

this is stored in palemoon.exe and xul.dll. Thanks ... I HexEdit-ed the only one instance of "28.1.0a1" inside the main executable (palemoon.exe) to "28.2.0a1" and this thing alone made the modded appVersion to be reported in most places that count, e.g. 1. The internal "about:" page 2. The dynamically constructed default UserAgent string... 3. The version used in/reported by the browser's Add-ons manager... 3. The version reported by the "Version in Add-on bar" extension... I had to nit-pick manually so that "28.2.0a1" be displayed in some other locations, like: 1. about:addons -> Themes -> Default 28.2.0a1 (I had to patch ./browser/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}.xpi file...) 2. about:support -> Version: 28.2.0a1 (32-bit) (This was very tricky to do; I had to hunt for and HexEdit two occurrences of the AppConstants.jsm file inside the main omni.ja file...). 3. Menu Bar -> Help -> Aboout Pale Moon -> Version: 28.2.0a1 (32-bit) (2018-09-21) (I had to patch an aboutDialog.xul file inside the ./browser/omni.ja file). Sadly, I was unsuccessful in identifying which file is responsible for generating the following pref: gfx.crash-guard.d3d11layers.appVersion;28.1.0a1 (which doesn't report 28.2.0a1, despite my modifications...); if anything, I learned a lot about the "insides" of the compiled browser's structure... Thankfully, with your most up-to-date New Moon 28 build, you are now in the 28.2.0a1 version string!

Hello again , I do hope life has gotten back to, somewhat, normal where you live, after that terrible natural catastrophe; the footage of Mangkhut ravaging SE Asia that we watched over here was daunting , to say the least... Back to the topic, if I understood you correctly, you said that a simple appVersion change doesn't merit a full clobber, which itself entails considerably longer build times, not to mention the increased power (electricity) consumption by the build-machine... If that's the case, I do understand, after all you know what's best for your building system... My only gripe is, if produced build stays in v28.1.0a1, this leaves room for some misinterpretation; 28.1.0a1 < 28.1.0, yet today's (Sat, Sept 22nd 2018) imminent NM28 build will be built on 28.2.0a1 code (i.e. newer that the officially released stable Pale Moon 28.1.0 build); and in any case, you will have to start building fresh at some point, won't you? It's the same thing with your Tycho builds, which still report v27.9.1a1, when in reality they should report v27.9.5a1... FWIW, the official unstable Pale Moon has been released on the 20th, appVersion="28.2.0a1", buildID (for win32)="20180919142716" and file version of palemoon.exe = 4.1.5.6836 One last question/request for help: Do you happen to know where exactly in the compiled browser modules is the actual appVersion string stored? I searched both omni.ja files (./omni.ja & ./browser/omni.ja) with 7-zip/NotePad++ and while I found some references, changing those and repacking the .ja files did not alter appVersion (I also use the Version in Add-on bar extension...) I echo everyone's sentiments here by saying you are a true life saver at this point for XP/Vista OSes, as practically no other browser (except your forks) is currently in active development for those OSes (... of course, credit also goes to MC Productions for maintaining original PM and Basilisk...) Keep well

As posted already by @roytam1, AppMenu items are not movable outside of the AppMenu button - this has always been the case in the pre-Australis Firefox GUI - OTOH, the Australis GUI has a native add-ons button which you can move and place where you please; FYI, Basilisk (Serpent) 52.9.0 browser comes with the Australis default skin/GUI... In the case of Pale Moon and forks (as well as Firefox < 29.0), if you want one-click access to the addons manager (AOM, about:addons) via toolbar button, in addition to what has been already suggested by Roy, you can install this simple extension from 2011: https://addons.mozilla.org/el/firefox/addon/aboutaddonsbutton/versions/ This works fine for me in NM28; one other option you may want to explore is: https://codefisher.org/toolbar_button/toolbar_button_maker/ where there's already a pre-made selection to create an "Add-ons toolbar button" extension...

Hello and welcome to MSFN forums! IMHO, you have a bigger problem in your hands by staying with Fx 28.0 ; it was released back in Mar 2014, still has a lot of unresolved functional bugs, not to mention that, security-wise, it has more holes than a piece of Swiss cheese... If you're clinging on it because it was the last pre-Australis major Fx release, then you can switch to latest, but EOL'd, FxESR 52.9.0 and install Classic Theme Restorer to regain 95% of the pre-Australis GUI+features; or install latest New Moon 28 build (a Pale Moon 28 fork modified so as to run on XP/Vista) that never implemented the Australis design... As for your original query: am afraid the answer is NO Fx 28.0 is simply too old; it does not support any form of EMEs (Encrypted Media Extentions = DRM components) and relevant CDMs (Content Decryption Modules), so installing Adobe Primetime CDM on Fx 28.0 is out of the question... On top of that, Fx 28.0 has no support for Media Source Extensions (MSE), needed for youtube MPEG-DASH streams; visiting https://www.youtube.com/html5 with Fx 28.0 on XP you should have got only HTMLVideoElement and WebM VP8 ticked in blue (i.e. supported); it would appear that youtube have retired the VP8 encodes, thus rendering Fx 28.0 on XP unusable... ; BTW, I'm not just speculating, I have got a portable installation of Fx 28.0 on an external HDD and by toggling media.windows-media-foundation.enabled (from true to false) I simulated an XP environment and conducted tests before posting this... On those of us on Vista and higher, Fx 28.0 by default has H.264 ticked in blue, because Fx 28.0 has support for Media Foundation, hence it has access to patented system decoders (h.264/aac) not present in the XP OS (by a M$ decision)... So I can still use Fx 28.0 on Vista on youtube, they serve me a progressive download (no MSE) of an MP4 encode... You want youtube in XP? 1. Use Google Chrome 49, or Advanced Chrome fork (or possibly other Chromium derivatives still supporting XP, e.g. Maxthon...) 2. Update to FxESR 52.9.0 ; native support for MSE+WebM VP9 (for other sites that require h.264/aac native browser support, follow the guides of this thread). 3. Update to New Moon 28 or Basilisk 52.9.0 by roytam1; both have native support for H.264/MSE+H.264/MSE+WebM VP9; (some) people on XP have encountered a small nuisance on Youtube, affectionately known as the "23min youtube bug"; it's not a deal breaker, TBH... And at least one person here has reported better aac (audio) decoding experience by disabling native support in Basilisk 52.9.0 and installing Adobe Primetime CDM there, as per this thread... Hope I made everything clear for you, I'm confident others can chime in for more detailed help, if you need it that is ...

OT: Of the 3 WMP versions that were supported in XP (9 -> 10 -> 11), my favourite one had always been WMP10 ; I was so sad I couldn't get it on Vista... I hardly ever used WMP11 on Vista, Winamp was my choice back then (ca. 2008), still have it installed, then tried Real Player SP, aka v12, but my current set of players includes MPC-HC (new fork is Vista+), MPC-BE (Vista+), VLC 3.0.4 (XP+), PotPlayer 1.7.xxxxx (XP+). On-Topic: Perhaps you can still upgrade to WMP11, to get the specified functionality, but use a WMP9 skin in it, to get the look you like... I found the following links: https://www.guidingtech.com/11798/apply-skins-windows-media-player-personalize-it/ https://www.howtogeek.com/howto/17560/apply-skins-to-add-a-little-flair-to-windows-media-player-12/ (The last one is for WMP12, however the same procedure applies to WMP11...). From my own copy of WMP11 (on Vista), the Revert skin preview looks a lot like WMP9: Tell us if it works for you...

On the official Pale Moon camp, Pale Moon v28.1.0 (stable) has just been tagged and released as source; I expect that Windows binaries be available imminently (most probably tomorrow, or the day after) ... Consequently, the unstable update channel, sourced from the master branch, has been bumped to v28.2.0a1; if over the coming weekend @roytam1 does clobber (as he should...) when building new binaries, NM28 builds will have the bumped appVersion and installed language packs (aimed at maxVersion=28.1.0a1) will get disabled... Just a heads up...

... Mozilla Firefox (and forks) uses its own certificate store, while IE and Google Chrome use the OS supplied one...

IE9 (32-bit) on Vista SP2 Home Premium 32-bit here The youtube.com/html5 test is correct when it comes to IE9 on Vista (no VP8 support here): IE9 has no support for MSE; after Google ceased supporting Adobe Flash Player (all 3 variants of it, i.e. activeX, NPAPI, PPAPI) on youtube, the only thing left for IE9 to handle was progressive download of mp4 files (encoded in h264/aac) over HTML5, and I recollect the limitation of not being able to go Fullscreen on the embedded player (a message about unsupported browser was displayed ) ... It was at the start of summer that I accidentally noticed yt was unplayable on IE9, as I'm hardly using IE9 for anything this day and age... I did not lament the loss of yt on IE9, in any case it had been an unsupported browser many moons ago already... But it was this thread that made me want to investigate things... So: Well, youtube claim they don't officially support any IE version anymore, yet tests show that IE10/IE11 still work, while (obviously) previous versions don't... Loading Introducing iPhone XS, iPhone XS Max, and iPhone XR in IE9 (after you declined to upgrade your browser, that is...), you get the empty embedded player, as per OP: For troubleshooting, open IE9's developer tools (F12) and load (browser) Console; refresh youtube page: To load their embedded player, yt use, among other things, a JS script named base.js; URI for my locale is: https://www.youtube.com/yts/jsbin/player-vflkUTZn2/el_GR/base.js That script uses in 19 instances the window.matchMedia code snippet; a Google search on matchMedia yields the following two results (among others): https://developer.mozilla.org/en-US/docs/Web/API/Window/matchMedia#Browser_compatibility https://caniuse.com/#feat=matchmedia where one can see that the needed API was introduced only in IE10+, i.e. IE9 does not understand window.matchMedia and chokes, failing to load the HTML5 youtube player: Mozilla Firefox, OTOH, supports the function from an early version 6 - and Chrome from version 9... Not strange anymore, is it?

As I'm sure you're already aware, the official Pale Moon web browser has no support whatsoever for EME and CDMs needed by Amazon Prime (and other similar services) on modern OSes and recent browser versions... However, it includes an Amazon Prime Site-Specific-User-Agent-Override (SSUAO) to force the service to fall-back on the Silverlight NPAPI web plugin; general.useragent.override.www.amazon.com;Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.9) Gecko/20100101 Firefox/45.9 (Pale Moon) It can be even simplified to general.useragent.override.www.amazon.com;Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0 The @roytam1 PM forks (NM27 built on Tycho, NM28 built on UXP) carry on this same SSUAO and can be run in XP|Vista; as I have no paid access to Amazon Prime, would you be so kind as to check how NM(27|28) fare on AP on XP? Amazon Prime site checks, among other things, the NT part of the client's UA and barfs when it's < 6.1 (= Win7); My gut feeling is that if you install a UA-changer extension on Google Chrome 49 (with Widevine installed) and fake an NT 6.1 OS, AP would work in GC+Widevine... Likewise in FxESR 52.9.0, you should install both UAcontrol+User Agent JS Fixer addons (as Fx does not support SSUAOs) and again fake a Fx 45 on Win7 user-agent... Please post back the results of your tests...

Hola! You have to install additional spell-checking dictionaries to your browser ; you failed to mention the specific browser you want this on (as roytam1 maintains several), but for Mozilla type browsers head over to https://addons.mozilla.org/es/firefox/language-tools/#desktop You probably want https://addons.mozilla.org/es/firefox/addon/spanish-spain-dictionary/ I have Moon Tester Tool installed in NM28 so I can install the Spanish dictionary straight from the AMO page; if it doesn't install for you, first download the .xpi file (diccionario_de_espanolespana-2.3.xpi) locally and then install manually... When on a text input field, you can select Spanish (es-ES) as spell checker via context menu: Or you can install a dedicated addon called Dictionary Switcher Best of luck...

Grazie mille for your recommendations I, myself, am not specifically out for video-downloading extensions, because, unlike other posters, for me IDM continues to play nice in NM28 with most sites, including Youtube, plus I use youtube-dl (CLI, or a GUI) for most of my media downloads ... NetVideoHunter has come up several times in the official Pale Moon forums as still compatible with PM28 and working so, yes, your suggestion could be of value to many members here... But, judging by the fact it was lastly updated Nov 2015, I don't expect it to cope well with youtube's constantly changing protection methods for copyrighted video+audio content (haven't tested it myself, just an educated guess here...).

Hello I currently do not have access to an XP laptop, but on my current Vista SP2 one, the "Connect to a Network" window dialog looks like this: That window lists all wireless networks picked-up by my WLAN card; if you hover mouse over one of them, pop-up (aka tooltip) has relevant info in the "Radio Type" row (e.g. 802.11n); I understand that window dialog is pretty similar in Win7 machines, but am unsure about the state of things in Win10... If you can't find a similar window in your XP laptop (I only ever had a desktop XP system, with only an ethernet LAN card...), perhaps you could inquire the radio type of your school's Wi-Fi by asking an IT staff member or another person already logged-in... Hope I've helped... (BTW, I'm in the range of a total of 10 different WLANs, including mine, only one of them is of radio type g, the rest are all n )

Sad but true... Who would have known... ?

Please read this, all of it... ... As you might already know, Windows XP SP3 doesn't have any WMF support, OTOH Widevine CDM (inside a "Mozilla" type browser) depends on OS decoders, accessible via MF, hence you also get: BTW, Most recent Widevine DLLs make function calls to APIs only present in Win7+; as I said in my other post, your best chance to get Spotify Web player working in XP is with Google Chrome 49 (you may have to make it appear as a more recent version to Spotify's APIs.)...

Sadly, it is no more : Since, as you said, there existed Webextension ports to the addon, it is unlikely AMO removed all traces of the extension in the framework of them culling all XUL (legacy) extensions from their online repo, a process that has (apparently?) started after Sep 5th, the date on which FxESR 52.9.0 became EOL...

... This is an already reported and known issue; last word on this from @roytam1 can be read here

Not quite... FxESR 52.9.0 (and later), as well as Basilisk (Serpent) 52/55 have this functionality as a native application feature, so they're not in need of the E-N-T extension; but this feature is native to the Australis (Fx 29-56) UI, used in both above browsers... Pale Moon (New Moon) 27/28 continue to use the pre-Australis (Fx 4.0-28.x) UI, and this lacks support for indicating tabs with audio content; to regain part of this functionality, on NM you have to install that special extension; I say part, because that extension only works in tabs with HTML5 audio(/video), whereas the native function in Australis Fx works even in tabs with an embedded Shockwave Flash player...

Hello The standalone windows executable, file youtube-dl.exe (32-bit, filesize 7.59 MiB ) has been compiled with Python 3.4.4 modules, which, AFAIK, is the last XP compatible Python version, most certainly not the latest (3.6.6/3.7.0). On my Vista laptop, issuing "youtube-dl --version && youtube-dl -v" in the command prompt window, in my yt-dl installation directory, I get: 2018.09.01 [debug] System config: [] [debug] User config: [] [debug] Custom config: [] [debug] Command-line args: ['-v'] [debug] Encodings: locale cp1253, fs mbcs, out cp737, pref cp1253 [debug] youtube-dl version 2018.09.01 [debug] Python version 3.4.4 (CPython) - Windows-Vista-6.0.6002-SP2 [debug] exe versions: ffmpeg N-91152-g7c333dc6a7, ffprobe N-91152-g7c333dc6a7, p hantomjs 2.1.1, rtmpdump 2.4 [debug] Proxy map: {} Usage: youtube-dl [OPTIONS] URL [URL...] My assessment is based on https://python.readthedocs.io/en/latest/using/windows.html#supported-versions While the latest release of the 3.4 branch is 3,4.9, every release after 3.4.4 has been made available only as source; the last XP compatible compiled installer is for 3.4.4, to be found here ... But even if/when in the future the yt-dl devs compile the standalone executable with non-XP compatible Python modules, all is not lost for XP users; yt-dl code has support for a variety of Python versions, methinks 2.6 to 3.7; so, an XP user can perform a full-blown Python installation on his/her system and then use the compiled zipped-executable version of yt-dl, file youtube-dl (size 1.62MB) on the GitHub Releases page... It can be invoked in the command line as python.exe youtube-dl [various yt-dl arguments] (you may have to use pip first to install additional python modules that yt-dl depends on, ones that do not come with the default (standard) installation on windows; but this is not a yt-dl support forum, ample info/help can be found on line already...) @Flame : While I spent 3 years on XP, I currently have no access to that OS (only to Vista SP2 32-bit + Win7 SP1 64-bit), so it would have been easier for you (... and me ) to get an answer to your query, had you kindly asked one of the many XP users that frequent this thread to test youtube-dl.exe for you (assuming you can't yourself...); but I didn't mind the challenge to answer it for you one single bit... Regards EDIT: @hotnuma beat me at posting, adding relevant information

... Nothing of this sort here... Trying a non-protected, non-music video like https://www.youtube.com/watch?v=I6M_vYUUx20 I can fetch without issues: I was curious to try a "protected" music video from VEVO, like https://www.youtube.com/watch?v=BilaShsQphM Even HD versions are available to download, provided I first select them in YT's embedded player (quality settings) Those MKV files contain VP9/opus encodes; if you are instead after a 720p MP4 file encoded in h264/aac, then you first have to disable (temporarily) Media Source Extensions (MSE) in NM28's settings Options -> Content tab -> Video -> uncheck MSE so that YT serves you that type of stream: If you're that interested in YT content, I'd recommend a specialised tool (not a browser plugin) like the constantly updated CLI app youtube-dl, if you're willing, that is, to work in the Windows Command Prompt... You should've created a separate support post and let @roytam1 know about this issue; needless to say, you should PM him log-in credentials too, if any hope of debugging this... Moonchilld have EOL'd Tycho (PM27), so 0 chances they address this now...

Latest builds announced by roytam1 here ; please also have a look at Roy's blog entries... Should create its own separate profile, but for good measure back-up any existing profile of Serpent52 on your system...

IDM integration v6.27.7 XUL ("legacy") browser extension is compatible with Firefox 52.9.0 ESR; since PM28XP is built on the UXP-T2 platform, forked from Mozilla 52.6.0 ESR, that same extension is compatible with PM28XP; sadly, it isn't installable out of the box, because its install.rdf file (inside extension's .xpi file) does not contain Pale Moon's GUID (={8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4}). You have two options: 1. Install "Moon Tester Tool" Pale Moon extension on NM28; open addons manager, locate MTT's entry there and access its preferences panel; click the Select file button and then navigate to IDM's installation directory (e.g. "C:\Program Files\Internet Download Manager") and select file idmmzcc2.xpi; it should now offer to install; restart browser and see the IDM addon installed and enabled! As you've already done, be sure to enable Pale Moon browser in the main IDM app's prefs... 2. Patch the existing extension version yourself; I won't provide a detailed guide here, but you should first decompress file idmmzcc2.xpi with 7-zip, open file install.rdf and after line 17 add a targetApplication block specific to PM: <!-- Pale Moon --> <em:targetApplication> <Description> <em:id>{8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4}</em:id> <em:minVersion>27.0.0a1</em:minVersion> <em:maxVersion>28.*</em:maxVersion> </Description> </em:targetApplication> Save the changes made; while you're at it, you can safely also delete dir META-INF, because PM does not enforce extension-signing... Re-zip modified contents of folder idmmzcc2 back to a idmmzcc2.xpi file and replace the original with it; restart NM28; if the extension is not picked up automatically, you may have to manually install it via drag-n-drop on NM28's addon manager tab...

@dencorso I'm probably just being dense due to the heat (34C here, on Sep 1st!), but you first quote a part of my post in which (part) I say nothing about Adobe Primetime CDM, then you proceed with discussing that same CDM; I don't get the connection... Yes, Mozilla has removed automated in-browser downloads (Bug 1337121, Bug 1304899) ... Do you actually mean that the CDM there is able to perform the role it was first designed for, decrypt DRM content? Please provide example cases... AFAIK, most DRM content providers won't use / don't support that deprecated CDM, either as a standalone decryption solution nor as a fallback when Widevine CDM is absent/disabled/non-functional... As I stated in that previous post of mine, so I can only surmise that by "still works OK" you are referring to that specific function of that CDM (which, for all intents and purposes, was not the reason it was conceived and bundled with the Firefox browser...). The Moebius platform both Basilisk 55 (by Moonchild - EOL'd) and Serpent 55.0.0 (by roytam1) build upon was forked from a Mozilla 53.0a1 platform snapshot; Mozilla themselves gutted out Adobe Primetime CDM support code from Firefox in Bug 1329543; mozilla-central Nightly-53.0a1 builds after 20170118 have no support for it; if Moonchild forked the platform from a snapshot after Jan 18th 2017, then it's safe to deduce Bk55 has no support, either; but I am uncertain of the exact code timestamp Moebius was forked from, so I'll leave the actual test to someone else... Most probably, Moebius has no support for that CDM... But Serpent 55.0.0 on XP does have native h264/aac decoding support, because roytam1 patched third party library ffvpx to include support for these patented codecs, too...

I am sorry to be the bearer of bad news, but if you're asking specifically for the Windows XP SP3 OS and the Spotify web player on a Mozilla type browser, there exist several serious reasons this isn't possible! 1, Spotify is one of the commercial media outlets that heavily use DRM for content protection; on Firefox and its forks, content decryption is delegated to CDMs (Content-Decryption-Modules), which are closed-source modules ("blackboxed") bundled with the open-source browser, to satisfy user watching/listening needs. 2. Mozilla had first incorporated Adobe Primetime CDM for the decryption of DRM'd content (a CDM familiar to XP users, as it is currently being "exploited" to enable h264/aac decoding support in the FxESR 52.x.x browser (... and some of its forks); this is not, however, a use intended initially by the Mozilla devs ), but that CDM was abolished in Fx 53.0+ in favour of the universally accepted, Google-owned, Widevine CDM. 3. As you probably know, all Mozilla browsers come without native support for patented decoders, like h264 (for video) and aac (for audio); if Mozilla went the "Google Chrome" way and bundled these decoders with Firefox, they'd have to pay annually huge sums of money as license fees to the patent holders (namely to the MPEG-LA group); they opted for a far less costly solution, that is to rely on system decoders (the ones bundled with the actual OS). 4. Speaking of Microsoft and the Windows OS, the first iteration of Windows with native h264/aac decoders came with the launch of Windows 7 OEM, though its predecessor OS, Windows Vista, was, too, equipped with similar support (be it less refined) when "Platform Update Supplement" for Vista SP2 was released via Windows Update.... Microsoft chose not to bestow h264/aac decoding support to Windows XP which is, in a way, the deal-breaker in your query... 5. Widevine CDM inside Firefox (or one of its forks) only executes decryption of the DRM'd media streams, the decrypted stream has then to be properly decoded to video and/or audio; Widevine in Firefox has been programmed to search for decoders only in the OS level (not the browser); remember that it is (very) closed source, this assumption is the result of tests only, no actual code for Widevine is, of course, publicly released... 6. Since Windows XP lacks native system decoders (and no, installed codec-packs don't work for Widevine), the Mozilla devs have disabled Widevine on XP, and only enabled it on Vista SP2 upwards; hence, minimum system requirements for services that employ Widevine on Firefox is WinVistaSP2+; however, since Vista has been EOL'd by Microsoft, this is currently read as Win7SP1+... 7. Specifically in the case of the Moonchild Productions' Pale Moon fork, because of their opposition to the closed-source nature of CDMs, they have purposely disabled DRM (CDMs) in the browser, so it's currently impossible to use DRM'd services (e.g Netflix, Amazon Prime etc.) in that browser, regardless of OS; the same holds true for New Moon 27+28, both Pale Moon forks... 8. Certain services that rely on Widevine did implement, at least in the past, a workaround when WV was absent in the browser, and that was to use the Microsoft owned Silverlight NPAPI browser plugin for both decryption+decoding; Silverlight has been deprecated by Microsoft and NPAPI plugins (except Adobe Flash) have been deprecated by all the major browser vendors, so using Silverlight in a browser as a WV fallback is pretty much a moot point; I am not subscribed to Spotify, so I can't be 100% sure it doesn't support Silverlight in Pale Moon (ergo New Moon); this chance is very bleak, if you ask me, though... 9. Of the rest of the "roytam1" browsers, excluding KM-Goanna and FxESR 45, only Serpent 52.9.0 and Serpent 55.0.0 were compiled with Widevine support, but, as stated previously, only if you are on Windows Vista SP2 or later; on XP, WV is disabled and doesn't show up inside about:plugins... (NB: Widevine on Serpent 55.0.0 on Windows Vista was initially non-functional (worked OK in Win7+), but this was rectified in https://github.com/roytam1/basilisk55/commit/cbc95b1 ; many thanks @roytam1 ) I wrote this analysis not only as an answer to your own query, but as a point of reference for other XP users... On XP, the only remedy I possibly see is trying to work things out with the last working version (49) of Google Chrome there; GC comes with its own version of patented decoders, and, AFAIK, has Widevine v1.4.8.903 inside; perhaps install an extension to fake a recent Chrome version to Spotify and see what comes out of it... Best of luck!