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On 28 August I received a blank email with just the sender and subject showing. Since then I have sporadically received completely blank emails, with no sender or subject, while others are arriving as normal. The same is happening when I open Thunderbird on my mobile, but not on my laptop which has an older version installed. It would seem that the issue is caused by update 153.1.1esr, as that was released on 28 Aug.

Can I revert to a previous version of Thunderbird or is there another way to fix this, thanks.

Good afternoon

I have been struggling to find some messages specific to specific dates and spend an awful amount of time tryomh yo access the correct one.

The solution proposed is a bit unclear to me, as it refers to "future folders". I need to unthread all my messages. Is this possible?

Thanks

PS The only version number i could find was for Firefox. There does not seem to be one for Thunderbird.

Hi there. The past few weeks whenever I try to view any YouTube embed on any website I just get this error and the video does not play: Sign in to confirm that you're not a bot

Of course I am signed in but it does nothing. It works in other web browsers, just not Firefox. I've tried resetting my cache and cookies, private windows, and disabling all extensions but nothing seems to work.

I used to be able to log into Peacock without issues. Either Firefox changed something or Peacock did. But it no longer works correctly. I can sign in, but the main menu appears for a split second, then the screen goes black.

When opening a new tab either by a link to another site or entering a url iOS Firefox reverts to another open tab while also opening the new site. This requires manual switching to the new url. Perhaps there is a switch I can change to have it go to the target url. Thanks for any guidance.

Hello,

My little brother signed me out of my mozilla account while trying to login to his school account using my computer yesterday. Now, even after signing his account out AND removing his account entirely from my firefox, I'm unable to login using my credentials on the "original profile" which is what I've always used. This is the message I get when trying to login:

This profile was previously synced to a different account To keep your data organized and secure, each Firefox profile can only be synced to one account. To sign in using (email)@gmail.com, create a new profile.

He wasn't even able to fully login with his account, and even after completely removing his account from my firefox (as far as I know) I'm not able to sign into the original profile at *all*, even though that's what I've always used. Does anyone have a solution for this?

Hi All,

I had several tab groups. I open and save and close them every day. but since yesterdayI cant find them at all. If I create a new tab group it appears but those old tab groups not! I've tested troubleshooting mode but noting.  

Firefox 154.0 (aarch64), macOS 26.6.2.

I have installed version 153 of Firefox for Android (see attached screenshot).

The release notes say that it supports importing bookmarks from csv files. https://support.mozilla.org/en-US/kb/importing-bookmarks-firefox-android says to tap bookmarks and then tap the menu icon at the top.

When I go bookmarks THERE IS NO MENU ICON (see attached screenshot).

What is going on?

Hello; I have been using Mozilla Thunderbird for many years on my PC and was wondering if I can start using my account on my Ipad or Iphone as yet?

          Regards
                           Mike Folley

I use nyt.com to assess my account with Firefox. lately, it has been very slow to load and when i click on an article, it is very slow to load.

With the new Firefox updates I no longer see my bookmarks. I tried the FAQ's and suggestions but I don't understand them. I need my bookmarks back ASAP! Tried ctrl-shift-B it did nothing.

About two months ago, after various Windows and Firefox updates, I can no longer make Firefox the default browser. In Windows Default Apps the only option for FF is to make it the default program for Adobe Acrobat Document. Choosing Make FF Default through the browser does not work either. Additionally, I’ tried numerous suggestions, using AI help offered by both FF and Chrome, without success.

The OS is not allowing me to make Firefox the default browser. Is there any way around this?

Any suggestions?

Firefox: 155.0.1 (64-bit) Windows 11 Pro Version: 25H2 OS build: 26200.9278

Thanks

(AI written summary of troubleshooting steps taken before making this support thread)

Firefox version: - 152.0.1 Release - 153.0 Nightly

OS: - Windows 11 build 26200

GPU: - NVIDIA GeForce RTX 4070 SUPER

Codec package: - Microsoft HEVC Video Extensions installed from Microsoft Store

Problem

Firefox does not expose HEVC playback support, causing Twitch to disable 1440p streams encoded with HEVC.

The same machine can play the same HEVC Twitch streams in Chrome immediately after installing HEVC Video Extensions.

Expected result

Firefox should report HEVC playback support and allow playback of HEVC streams, as Chrome does on the same system.

Actual result

Firefox reports HEVC as unsupported.

about:support:

codecSupportInfo: H264 SWDEC HWDEC VP9 SWDEC HWDEC VP8 SWDEC HWDEC AV1 SWDEC HWDEC HEVC NONE

Troubleshooting already performed

- Installed Microsoft HEVC Video Extensions - Rebooted Windows - Updated NVIDIA drivers - Verified hardware acceleration is enabled - Tested with a brand new Firefox profile - Tested with Firefox Nightly - Confirmed Chrome can play the same HEVC streams

Additional observations

Chrome: - Twitch 1440p becomes available immediately after installing HEVC Video Extensions - Twitch Stats for Nerds reports:

 hev1.1.6.L150.90.0.0.0.0.0

Firefox: - Twitch reports that the browser does not support the required resolution - 1440p remains greyed out - about:support continues to report HEVC NONE

Reproducible tests

Firefox console:

MediaSource.isTypeSupported('video/mp4; codecs="hev1.1.6.L150.90"')

Result: false

MediaSource.isTypeSupported('video/mp4; codecs="hvc1.1.6.L150.90"')

Result: false

navigator.mediaCapabilities.decodingInfo({

 type: "media-source",
 video: {
   contentType: 'video/mp4; codecs="hev1.1.6.L150.90"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: false,
 smooth: false,
 powerEfficient: false

}

For comparison:

MediaSource.isTypeSupported('video/mp4; codecs="av01.0.08M.08"')

Result: true

navigator.mediaCapabilities.decodingInfo({

 type: "file",
 video: {
   contentType: 'video/mp4; codecs="av01.0.08M.08"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: true,
 smooth: true,
 powerEfficient: true

}

Additional note

Setting:

dom.media.webcodecs.h265.enabled = true

causes HTML5 codec test (https://html5test.co/) to report H.265 support, but does not change:

- about:support - MediaSource.isTypeSupported() - MediaCapabilities.decodingInfo() - Twitch HEVC playback availability

Question

Is this a known issue with HEVC Media Source Extensions support on Windows 11 build 26200, or is there another requirement for Firefox to expose HEVC playback capability through MediaSource and MediaCapabilities when the Windows HEVC codec is installed and functioning in Chromium-based browsers?

I have been unable to add Yahoo as the default search engine. No matter what address I type in, it consistently comes up with "Could not add OpenSearch Provider for".

I have an email account on Thunderbird that I no longer use that I want to delete that account. I can very easily add an account to Thunderbird, but I can't seem to find any way to delete one. Is it even possible to delete an account?