Thunderbird Community Forum

• • Subject: Severe recurring UI freezes after upgrading Thunderbird from v114 to v150+ — application becomes unresponsive after being left idle**

Hello Thunderbird Support Team,

I'm experiencing a serious and persistent performance issue with Thunderbird that began immediately after upgrading from version 114 to version 150 in September 2026. The problem has continued through multiple subsequent updates and is now severely affecting my daily work.

I've been using Thunderbird for years, and it worked reliably before this major upgrade.

• • The problem**

Thunderbird launches normally and initially works perfectly. However, after I leave it open in the background while working in other applications, it frequently becomes completely unresponsive when I return to it.

Specifically:

- Thunderbird is initially fast and responsive after launching. - After approximately 5–10 minutes, or sometimes after a longer period of inactivity, it begins experiencing severe lag or freezes completely. - When I switch back to Thunderbird, the interface is often unresponsive for several minutes. - I often have to force-close the application through Windows because it becomes practically unusable. - Restarting Thunderbird temporarily restores normal performance, but the problem eventually returns, when it's left idle. - The issue occurs repeatedly throughout the day and makes it very difficult to use Thunderbird reliably.

Importantly, this is not simply slow startup performance. Thunderbird initially works perfectly, and the freezing develops after it has been running for a while, particularly when left in the background.

• • Version and environment**

- Operating system: Windows 11 Pro, 64-bit - Thunderbird version before the upgrade: 114 - Version initially upgraded to: 150 - Subsequently confirmed version: 156.0.1 (64-bit), on September 29, 2026 - Problem first appeared: September 2026 - Problem still present: October 22, 2026 - Current Thunderbird version: 158.0.1

• • Troubleshooting already performed**

1. **Global search indexing:** I noticed that Thunderbird's Activity Manager frequently displayed "Indexing messages." I suspected that indexing might be causing the problem.

2. **Disabled Global Search and Indexer (Gloda):** Unfortunately, this made no meaningful difference. Thunderbird continued freezing even with global indexing disabled.

3. **Multiple Thunderbird updates:** The application has been updated repeatedly since the initial upgrade, but the freezing has persisted.

4. **Restarting Thunderbird:** Temporarily resolves the problem, but only until Thunderbird has been running for some time.

• • Additional unusual behavior: Google OAuth authentication**

On at least two occasions, after force-closing an unresponsive Thunderbird process, Google Chrome unexpectedly opened a Google authorization page saying:

"Mozilla Thunderbird Email wants access to your Google Account."

The page also indicated that Thunderbird already had some access to the Google account.

After clicking "Continue," Chrome redirected to a localhost address (127.0.0.1 equivalent, using a dynamically assigned port), which failed with:

"ERR_CONNECTION_REFUSED — localhost refused to connect."

I suspect this happens because Thunderbird is no longer running to receive the OAuth authorization callback.

I'm not sure whether the Google authorization issue is directly related to the freezes, but the repeated timing is suspicious and could indicate a background synchronization or authentication problem.

• • Impact**

I use Thunderbird extensively for professional correspondence and managing my translation business. These recurring freezes are seriously disrupting my workflow.

The problem has now persisted for over a month, despite updates and troubleshooting. It is becoming increasingly difficult to continue using Thunderbird in this condition.

• • What I would appreciate help investigating**

Could you please advise on how to identify the background process or operation that causes Thunderbird to become unresponsive after it has been running for several minutes?

In particular, I would appreciate guidance on:

- Whether this is a known regression affecting users who upgraded from much older Thunderbird versions. - Whether IMAP synchronization, background authentication, or Google OAuth activity could be responsible. - Whether there are diagnostic logs or performance profiles I can collect while Thunderbird is frozen. - Whether a particular database, profile component, or setting could be responsible without requiring me to rebuild my entire Thunderbird setup. - Whether there are known fixes or workarounds.

I'm happy to provide additional diagnostic information, screenshots, or logs if that would help identify the cause.

I would particularly appreciate a way to capture what Thunderbird is actually doing during these freezes, rather than continuing to try speculative troubleshooting steps.

Thank you in advance for your assistance!

When I want to insert images into an email, I use the "Send via email" option. I am then prompted to "Select image size," after which I click "Attach." At this point, a Thunderbird window should open with the files already attached—but it doesn't. What am I doing wrong?

I have read the topic "Microsoft EWS to Graph Migration October 2026". I have followed the instructions meticulously MULTIPLE TIMES. Unfortunately for me, it DOES NOT WORK!! After deleting the EWS account, I proceed to create the new Graph account, but it fails (has failed) EACH AND EVERY TIME I've tried it. I finally had to give up, and restore/re-install/setup the Thunderbird EWS version. The failure reported on each failure was an "authentication failure".

My OS is macOS Tahoe 26.7.1; My Thunderbird version is 158.0. This is distressing! If there is an issue, I would expect T'bird to belay the update until the issues were fixed. If there is a "trick" required, I would appreciate someone sharing it with me. I'm aware that the causes of these issues is "Microsoft Incompetence", but AFAIK incompetence is not "contagious" - I don't understand T'bird/Mozilla releasing a fix with detailed procedures without testing.

EDIT: One other piece of information that may or may not be useful. The article "Microsoft EWS to Graph Migration October 2026" mentions a "Microsoft 365/Exchange Online email account". My account is an "Exchange Server" account; the Exchange server is hosted by Microsoft.

Thanks for any advice.

Best Regards, ~JM

After 158.0.1 update the colors are broken when I open a calendar event (in a popup or tab) in edit mode the description has dark background with black font which is very hard to read. I have Dark Mode in windows and this issue is in both Auto and Dark themes in Thunderbird. No matter what theme I install apart from Light the description in unreadable.

Hi,

I just had to reinstall Windows 11 on my desktop computer because Windows Update would not update anything. It would start to install the update and upon the first reboot, it would fail with 0xc000021a and would back out the update. I tried updating Windows while keeping my data and it would fail at the first reboot with the same code.

I made note of where Thunderbird stored the profile (C:\Users\rayli\AppData\Roaming\Thunderbird\Profiles\pghy27s4.default, and C:\Users\rayli\AppData\Local\Thunderbird\Profiles\pghy27s4.default).

Prior to starting the wipe and reload installation I made a System Backup (using EaseUS ToDo Backup Home) of my boot drive (all 4 partitions). After the new copy of Windows was running I used the backup program to restore the above 2 files to the original location.

I then downloaded and installed the latest Thunderbird from the website and before I launched it the first time, I launched the Profile Manager from Terminal (Admin) and my old (restored profile) was not listed. I shut down the Profile Manger, launched Thunderbird, and proceeded to add my Comcast email account and my Gmail account.

What I need help with is recovering the 2 address books from the old profile and a folder where I save emails to.

The current profile is stored in "C:\Users\rayli\AppData\Roaming\Thunderbird\Profiles\9nfxwsrx.default-release". The profile containing the info I need is in the same folder and is named "pghy27s4.default". I added a screenshot of the folder.

Note that I also have an SSD that I cloned my old system to, which I can install in my computer and boot from. My system has a second SSD (it is D:) that contains a lot of my data, so I can copy whatever I need to it.

With a previous Windows 11 reinstall-in-place attempt, I had used the Export function of Thunderbird to backup the profile. After updating Windows 11 I installed the latest Thuderbird and tried the Import function but it failed before completing the Import, so I did not Export this time.

Hello,

I'm moving to Graph from EWS and have followed the instructions at: https://support.mozilla.org/en-US/kb/microsoft-ews-graph-migration

I get through to screen that offers Graph API as an option, alongside IMAP, POP3 etc, and click on Graph API which directs me to my browser to log in to my email service (via GoDaddy). I log in successfully which takes me to the Thunderbird 'You're All Set' screen saying the account has been securely connected to Thunderbird and therefore ok to close that screen.

Back on Thunderbird it then progresses but returns with "Authentication Error - unable to log in at server. Probably wrong configuration, username or password".

The username and password are correct, and there aren't any other options available when editing/manually configuring the connection...so at a dead end, alas.

Any pointers much appreciated!

Example why question is being asked:

Three separate GMX email accounts, each with its own unique password, and NOW Application-specific password for Thunderbird. Aliases are not used or desired. Three different separate accounts that should each have its own outgoing server.

Worked fine until updates to Thunderbird and changes to the GMX server, and Application-specific passwords became a requirement to send and receive email.

Seems like updates to nearly every program and/or app that may be released with the intent to resolve an issue or include a new feature breaks something else. M$ is horrible with updates and labels nearly everything as a critical update so it gets pushed through even when updates are turned off or supposedly permanently disabled by a registry hack; Windows 11 being the absolute worse ever. Why I only have one computer with M$ while all the others are Linux. Problems all the time with M$ while Linux simply continues to work.

Regardless, can setup each GMX account but the default email account name must be used as the user name on the other two GMX accounts on the outgoing server in order to send email. Then the recipient sees the name for the default account rather than the name assigned to the other two accounts, and the Application-specific password for Thunderbird must be changed to that of the default. Then attempting to pull down email for the other two pop accounts comes to a halt, and email messages can only be viewed by going to the online account.

Two separate accounts for yahoo, two for gmail, and one for Charter work fine, each has its own name and outgoing server. Should be the same way for GMX but is not because Thunderbird requires one of the three GMX accounts is set to Default.

Appears by having a Default email account, users are not only restricted by the default account, but email that is sent is done so with he incorrect name, The purpose for three different emails is for email segregation and better management; personal correspondence, business related, and Internet stuff.

Instead of having a 'Default' email account, makes more sense to use a valid email to register Thunderbird after downloading and installing, and then using that email for Support, Boards, assistance, etc. The default email requirement causes too many frustrating unneeded issues that should not occur, along with wasted time, stress and grief. Computers were suppose to make our lives easier and allow us more time for the real world. Biggest lie told since the Bell Labs created the transistor.

Thunderbird 158.0.1 (64-bit) Thunderbird codename Meadow badgeMozilla Thunderbird Flatpak en-USthunderbird-flatpak - 1.0

Computer OS:

 Kernel: 7.0.0-38-generic arch: x86_64 bits: 64 compiler: gcc v: 13.3.0 clocksource: tsc
 Desktop: Cinnamon v: 6.6.9 tk: GTK v: 3.24.41 wm: Muffin v: 6.6.3 vt: 7 dm: LightDM v: 1.30.0
   Distro: Linux Mint 22.3 Zena base: Ubuntu 24.04 noble

I have a laptop with win 11. Thunderbird gives the "managed by an organisation message" which seems to be related to bitdefender, which i don't have on the laptop and don't even know f I ever did - maybe I copied it over from Thunderbird on my PC?

See screenshot - the programme Everything flags up various bitdefender stuff, but won't let me delete them. What should I do?

I notice that in dark mode highlighted text and color text are rendered as normal white text. This behaviour broken UI experience because those style are used to give more importance to some text and in this way this intent is totally lost.

I attach some example switch from dark to light mode.

I think that is useful adding an option to use dark mode without overwrite this type of colors

I have just starting using Thundermail and one thing I am trying to understand better is Address Books in Desktop Thundermail in Windows 11.

I now have the following under address books: All address books (assume that this is just everything in all the address books), Personal Adress Book (empty), Contacts ( not sure where it comes from, probably 1 or both of the 2 emails of mine I have connected), Contacts (not sure where this came from but looks suspiciously like it comes from my gmail email or emails? as it is a long list), Thundermail Address Book (empty), Collected Addresses (looks like it picks these up from emails I send or receive).

I am interested in understanding what forms this initial list of address books, do they continue to reflect changes in the original source address books from outside or are they a once only transfer?), how I can manipulate them, probably to end up with: All address books, and other address books continuing various subsets for convenient access to a smaller list of contacts under these sub address book names.

Can I easily copy or move addresses between address books? Documentation already answering many of these questions may already exist? Thanks for any help or advice you may be able to provide.

Stop the Inbox from minimizing when I use the Search box. I have t open Settings for the InBox to be found again. Is there a newer version? I have 158.0 (aarch64)

Since Thunderbird Meadow the calendar in broken in dark mode. If one tries to edit an entry, one is greeted with black letters on black background. Prior to this it was at least in white letters and changed to black in light mode. Wonder when this will be corrected??

If Desktop Thunderbird has been around for many years, why does it still have so many problems? I am having no end to the problems in trying to connect my to Gmail accounts effectively. This should be simple?

The note said "You are receiving this message because according to our records, you have recently logged into your . . . Google account using an outdated protocol (IMAP). This is usually through an external application such as Apple Mail or Outlook. We will be applying some security updates on October 28th, including disabling access to email via IMAP. Apple Mail and Microsoft Outlook use IMAP so these will no longer work after IMAP is disabled. You should start using the web interface on your computer and the GMail App on your iPhone immediately to make sure that you don't miss any emails.

So does this mean I won't be able to use Thunderbird any more?