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Hi all,

I've been using Thunderbird for eons but yesterday morning it started freezing up constantly.

It freezes up ("Thunderbird is not responding") every time new emails are received or any time I take any action while the Inbox folder is open. So, if I delete an email it freezes for a few minutes. If I do anything pretty much, it freezes up for a few minutes. Then it comes back and I can do another action, and it freezes again. This only seems to be happening when I have the Inbox open - if I go to other folders it seems to function normally.

Things I've tried without success: - Troubleshooting mode - Adding exceptions for my profile folders to Windows Defender - Compressing Inbox (and Trash and Junk) - Repairing the Inbox index

This doesn't appear to be a memory issue - right now, memory use for my entire system seems to be hovering at just over 50%. But Thunderbird is still freezing.

My Inbox folder is very large, but it's never been an issue before and nothing significant was added yesterday when it started failing.

Any suggestions appreciated!

Thanks

Yesterday I had to change my Spectrum email - I have an old road runner email address and swapped over to spectrum.net server from the old server. In this process I had to update my password to access the server.

When I updated per the instructions from Spectrum I was able to do a normal download into my Thunderbird inbox. This triggered me having to input the new password. I did check the box to update the password and save it. After the one time download I cannot get Thunderbird to download emails. I can send emails with no problems but cannot download. No way can I get a download - it does not on initialization, at the set time nor with the manual request.

Spectrum is no help - their web mail works and it's my problem. I realize this is an old system, legacy and all that - anybody got a magic fix?

Any idea on how I messed this up?

Thanks.

I've been using T-bird since nearly the beginning, and I've always been able to search for a string in a message by hitting the slash ("/") and typing my search string. This appears to be a shortcut for Ctrl+F (on Windows, currently Windows 11).

With T-bird 151.0, when I press "/" it is ignored... the first time I use it. If I press Ctrl+F and do a search, then I can start all subsequent searches in that message with a slash. If I close that message and open another, I must again use Ctrl+F the first time I want to search.

My muscle memory constantly forces me to type "/<string>" to search, but since T-bird ignores the slash, the following characters immediately take action, usually causing me to navigate away from the message, mark them as read/unread or as junk, etc.

Since I can use "/" on subsequent searches, I'm thinking this is a bug, not a feature removal. Can this be checked/confirmed? ...thanks!

I just installed Firefox on my PC haven't had it on this computer since reinstalling windows - I imported my bookmarks and passwords from Edge, thinking it would be a seamless transition, since I used Firefox in the past without much trouble.

Two weeks on, about 95% of every page I open gives an error similar to the one below, and I have to shift+refresh several times to get it to reload before it goes away, (some sites still don't open).

I wonder how common this issue is, and how people fixed it?

Be careful. Something doesn't look right.

Firefox spotted a potentially serious security issue with connect.mozilla.org. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails.

Go back (Recommended)

Hide advanced

Advanced What makes the site look dangerous? The site is set up to allow only secure connections, but there's a problem with the site's certificate. It's possible that a bad actor is trying to impersonate the site. Sites use certificates issued by a certificate authority to prove they're really who they say they are. Firefox doesn't trust this site because its certificate isn't valid for connect.mozilla.org. The certificate is only valid for: *. eero.com. What can you do about it? Probably nothing, since it's likely there's a problem with the site itself. Sites use certificates issued by a certificate authority to prove they're really who they say they are. But if you're on a corporate network, your support team may have more info. If you're using antivirus software, try searching for potential conflicts or known issues. View the site's certificate Learn more about secure connection failures Error Code: SSL_ERROR_BAD_CERT_DOMAIN Jun 5, 2026 10:58:34 AM GMT+10

Proceed to connect.mozilla.org (Risky)

I have selected the 4 rows for shortcuts on my tab and have installed all but the last 3 spaces in the end of the 4th row. There's no option whatsoever to continue to add those remaining 3 spaces. Any suggestions?

After Windows 11 Home's Microsoft password manager supports passkey, I have troubles with passkeys in Microsoft password manager, not Windows Hello.

1. Firefox failed to login into sites with passkeys in Microsoft password manager tied with sites.
2. After Firefox added a passkey into Microsoft password manager (at that time, no error occurs and display succeed messages), Firefox an Microsoft Edge (Chromium based) fails to login by the passkey. And this trouble continues after Edge replaces the passkey tied with the site.

So, I can't use passkeys in Microsoft password manager.

Have you heard something like this troubles?

OS: Windows 11 Home 25H2 (Japanese locale) Firefox 151.0.3 (x86_64 with Japanese locale. On second trouble, I used the latest version at the old time) Edge: 149.0.4022.52 (Official build with Japanese locale)

I'm not sure exactly when this problem started but it could have been when I had to move my primary email from Xfinity over to Yahoo. Also not sure if this started after a recent Thunderbird update. I can not send new emails nor can I forward old emails. Haven't tried reply but suspect it is the same. This is the message I get: Sending of the message failed. An error occurred while sending mail. The mail server responded: Request failed; Mailbox unavailable. Please verify that your email address is correct in your account settings and try again. All settings and passwords are correct as I can receive and send from all my different accounts using browser. I can send emails from my accounts, on my iphone, though not using Thunderbird on iphone. Account settings and passwords are the same on the phone.

A client of ours has recently raised an issue with with us stating where right-click, Paste does not work when adding text to a new LinkedIn post

After investigating, we have been able to reproduce the same behavior on our devices.

However, from our testing, we can right click to past on comments, messages and searches just fine

Troubleshooting already attempted:

Cleared Firefox cache Performed Firefox refresh Tested across multiple devices

We have confirmed this occurs on:

Clients device My work desktop My work laptop My personal desktop My Personal Macbook

This issue appears to have started after updating to Firefox version 151.0.0. I know this as i have tested this on my work laptop, appeared to work fine then stopped working after manually updating from 150.0.3 to 151.0.0.

Please let us know if there are any known issues, additional troubleshooting steps, or if further diagnostic information would help I have attached screenshots of the issue.

I have also tested this in the Google Chrome web browser and appears to be working correctly as also seen in the screenshots.

I have been having troubles logging in with my Microsoft email account on Thunderbird (hotmail). When I fill in the name and email address, a pop-up appears with the OAuth2 authentication but the only thing that ever appears in this pop is the message "Unable to connect" with some additional possible explanations.

I have looked online a lot for solution but nothing seems to work. I have cleared the cache, removed all mentions of the email account (it was working before until I added a passkey to the account).

Other reasons I have seen is that the request might be intercepted by certain problems like Apache or Nginx etc. I am running an instance of Nginx on my home server, which is a different device. But I have temporarily turned it completely off but it did not change the situation. The same story with and instance of PiHole, it turns on my homeserver which is a different device and also had to turned off.

The machine I am running Thunderbird on is a Windows machine. I have also tried booting into safe mode with networking but also that did not do anything.

I have tried copying the url on the top of the pop-up window and pasted into several web-browsers. There is does load and I can select the correct passkey to login. But the data that comes back from it is not being given to Thunderbird of course so it does nothing. But the fact that it is able to load outside of Thunderbird makes me think it is a problem on the side of Thunderbird.

Could you perhaps help me set up my email on Thunderbird?

Adding this post for SEO indexing purposes, as I cannot reply to the original archived one: https://support.mozilla.org/en-US/questions/1321170

The original post is one of the top search engine results, and provides a bandaid solution, without addressing the proper root cause, so I want to help whoever stumbles over this.

Original problem:

Dale 1/9/21, 8:26 AM

Firefox Developer Edition 85.0b4, macOS 10.15

If I Google for a PDF and click a link, I get the Firefox download dialog. If I select "Open with Firefox [Developer Edition]", the following things happen:

   The PDF is downloaded to ~/Downloads
   The PDF is opened in a new tab, with that new tab's location bar holding a file:///... URL to the downloaded PDF 

What I would instead like to happen is:

   The PDF is downloaded to some temporary directory where I won't have to worry about deleting it manually
   In whatever tab the PDF is displayed in, the location bar contains the URL where the PDF was (temporarily!) downloaded from 

How can I achieve this?

Not having the URL where a PDF was opened from is very annoying when, for example, I open a bunch of PDF search results to read and review, and I later want to share links to some of those PDFs. Best I can do to find their URLs to give to others is then to try and remember which tab corresponds to which search result, or do mine the downloads tab.

Contrast this with Chrome: I click a Google result for a PDF and the PDF just opens in the current tab with the URL to the PDF in the location bar. No dialogs, no PDF files hanging around in my home directory, and I can just copy the URL to the PDF the same way I'd copy the URL to any web page.

Thank you!

Proposed solution by original poster:

Dale Question owner 1/9/21, 9:27 AM Chosen Solution

Sigh. It appears the problem was one or both of the following preferences:

   pdfjs.enabledCache.state: false
   pdfjs.migrationVersion: 2 

I deleted both, and now clicking on a PDF just opens in the sane, normal way in Firefox that I desire.

Naturally I have no idea how those got set.

I installed Firefox Developer Edition and I am having the following issues, whenever I go to Indeed and I go to a job posting the browser opens up additional tabs without my permission or me doing so. Also the browser does the same in Canvas when I go to my course the browser automatically opens up new tabs without my permission and also me doing so. The Firefox Developer Edition browser update is Firefox Developer Edition is up to date 152.0b7 (64 bit). The following extensions are installed AdBlocker Ultimate, FoxyProxy Basic, Ghostery AdBlocker For Privacy, Malwarebytes Browser Guard, Privacy Badger, and UBlock Origin. This behavior got super annoying and I don't know how to fix it. Any help on how to fix this would be appreciated. My operating system is Windows 11.

Hi, I am hoping that the community can help me find an answer to this. I have two computers that I use for work. The one in the office has TB running all the time and before I leave for the weekend/vacation I would close TB, copy the profile folder to a USB (or copy it to cloud) and then paste the profile folder on my work laptop (at home). While all the settings get copied (local folders structure, addons etc.) as I use IMAP, it downloads all the mail on the new system regardless. I thought that it should have the latest mail downloaded as part of the profile folder, is that not the case? The bigger issue is that none of the Completed Tasks Lists, Templates, etc. get updated. It still shows all the older stuff on the work laptop and no updates carry over from the PC (at work). Going through the profile folder I see multiple copies of the files prefs.js, folderCache.json, global-messages-db.sqlite appended as: prefs-computername.js and folderCache-computername.json etc. (The computername is the name of the PC - office/laptop) The profile name is the same between the two computers. TB is only started after the profile is copied locally. TB version is the same between systems. I am left scratching my head why somethings are copied but not others. Hoping that the community can help me here. Thanks!

I have several Windows 7 computers running Thunderbird and have 13 POP3 accounts to retrieve. These computers work fine. It takes about 5 seconds to check all 13 accounts if there is nothing new to download. I have two Windows 11 computers that take about 50 seconds to go through these same accounts under the same conditions (nothing new to download). I have done a lot of searching for answers, but nothing helpful has come up. Any ideas on what might be causing this? Seems like it would be a common problem as both Windows 11 computers do the same thing. Both are Windows 11 Pro. Thanks for any guidance.

I am using Windows 11 with the latest Thunderbird 151.0.1. I have been trying to add color to the column title background in the message list using the userChrome.css with the following:

1. sizeCol {background-color: #dcfffc !important;}
2. recipientCol {background-color: #dcfffc !important;}
3. subjectCol {background-color: #dcfffc !important;}
4. dateCol {background-color: #dcfffc !important;}

1. spamCol {background-color: #dcfffc !important;}
2. fromCol { background-color: #dcfffc  !important;}
3. attachmentsCol { background-color: #dcfffc  !important;}

They work except the 'from', 'attachments' and 'spam' columns title backgrounds. Can anyone see what I am doing wrong? Or is there a way to color all column title backgrounds in one line? Thanks