Thunderbird Community Forum

Whenever I start my PC, the first time I click on the Thunderbird icon at the bottom of my screen (is that still called the taskbar?) I have to click on it a 2nd time to get it to open. After that I only have to click on it once. Does anyone know I can get it so I only have to click on it once the first time as well as understand what may be causing this problem?

My Thunderbird connected to my gmail is running slow. Thunderbird is not running slow on my other (non-gmail) account. It takes 10-15 seconds for an e-mail (from gmail) to be deleted or moved within Thunderbird. I have tried "compacting folders" and "repairing folders" and that does not help. Please help!

It's very odd. Normally moving an email, say from the Inbox to the relevant year's archive, takes "no time at all".

Which is true for all the mailboxes shown on the attached screenshot, EXCEPT for the four at the bottom. Moving even one message from Inbox to Yiddish can take ten seconds or longer (with the dreaded "Not Responding" occasionally). Moving something in the opposite direction is also screwy, only from those four.

I had thought that it was because they're rather large. This first started when there were just Yiddish and MSW, and I split off most of the earlier years into the archives shown. To no avail.

It's only an annoyance, but I'm puzzled about how such a thing could happen.

Also very slow tagging or untagging a message just in those mailboxes.

Moderator Notes:

• need a performance profile https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance

On my Windows 11 PC, when I open my Thunderbird Address Book and click on any entry, or right-click and select any option, a solid grey veneer overlays the Address Book window, and nothing else happens: The feature hangs. I can close the window and continue to use Thunderbird, but all I can do in the Address Book is scroll through the names and email addresses. When this first happened, I updated Thunderbird to release 159.0 (64-bit), but the same thing happens in that version. I've done web and forum searches and have not seen any other reports of this. Any ideas as to why this is happening to me, or how I might fix it? (I've attached a redacted screen image showing what I see.)

I have noticed that Thunderbird has been very slow and glitchy very recently.

Some messages take ages to load. Sometimes the whole program hangs and becomes unresponsive.

My question can suffice. Once I installed Thunderbird release over the Thunderbird ESR, I have very slow or no access to messages sent before my account was converted to Graph. Confirm?

recently, e-mails have been hanging. I have determined that it is, for the most part at least, USPS mail tracking e-mails that hang. Once I delete or move to archive, things download fine.

This is not the daily Informed Delivery e-mail.

This is like "your package (tracking number nnnnn) has arrived at the distribution center. Expected delivery mm/dd/yyyy.

I have restarted, repaired in box, etc.

Any help?

Thunderbird has become extreme slow. Like it's doing task in the background. Takes emails longer to display and mouse becomes jerky. All other programs OK Especially noticeable after leaving TB running for a while. The previous versions were snappy. This version is very noticeably slower.

My Thunderbird (158 Meadow) is very slow sending emails. Up to 30 seconds for an ordinary message. Most often thew people are in my address book but even if they are no the problem is common across all outgoing emails. Windows 11 Laptop 26H2, 64Gb Ram, 500Gb SSD, 200GB free, i7 (12 Edition) Intel I have already checked that my Windows Defender antivirus has the profile folder as an "exception" Compressed my "send" folder Run "repair" on my send folder I have about 500 emails in my send folder I have an IMAP set up with SMTP set to 465 SSL/TLS Normal password I have checked my webmail and that works fine so it is not a problem with hosting etc.

I am unable to access my emails in Thunderbird. Thunderbird opened but does not respond as there appear to be some files /emails that it could not accessed.

I tried deleting the Parent.lock file. I then deleted Thunderbird and re-installed it.

On opening the updated instance, it comes up with the same couple of files/emails in the list. With the same ones seemingly trying to be loaded. See attachment. The files are Invoice 03-10-20 and Ticket_1.pdf

• • 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!

I was referred here from Thunderbird Bugzilla report 2081665.

We are experiencing a recurring problem with Thunderbird 153 on several Windows workstations in a business environment.

The important point is that the problem also occurs with completely new Thunderbird profiles created from scratch. It is not limited to migrated or old profiles.

On one workstation this has already happened to three separate Thunderbird profiles.

Typical sequence:

1. Thunderbird 153 is installed. 2. A completely new profile is created. 3. Mail accounts are configured manually. 4. Everything initially works normally. 5. After some time the profile begins to malfunction. 6. Thunderbird Settings no longer open/respond. 7. The address books still exist, but address autocomplete when composing a new message stops working. 8. Creating another new profile temporarily fixes the problem, but the same behavior can return later.

Troubleshooting already performed:

- Troubleshoot Mode - extensions disabled - tested without the existing prefs.js - rebuilt Thunderbird caches and profile UI state - recreated indexes/databases - completely removed Thunderbird from Program Files, AppData\Roaming and AppData\Local - clean Thunderbird installation - clean profile created from scratch - Thunderbird executable and profile paths added to Kaspersky Endpoint Security trusted applications/exclusions

Removing prefs.js from an already affected profile did not restore the Settings window.

A clean test profile initially works correctly.

We have also encountered this behavior on other workstations. Some users have more than 100 message filters and many folders, so rebuilding profiles repeatedly causes significant administrative work.

Several affected computers had Windows user accounts renamed in the past.

We also experienced a separate issue where the Attach File dialog stopped appearing while drag-and-drop still worked. Bugzilla identified this as the already known Bug 2077590, so I consider that a separate issue.

For comparison, after completely cleaning Thunderbird from an affected workstation and installing Thunderbird 115.3.1 with a clean profile, the same workstation currently works normally.

Because freshly created Thunderbird 153 profiles can later develop the same problem again, simply recreating the profile does not appear to be a permanent solution.

Environment:

- Windows workstations - Thunderbird 153 ESR - Kaspersky Endpoint Security - multiple IMAP accounts - business environment

What diagnostic information should I collect from the next affected profile before replacing it?

I can provide:

- Thunderbird Troubleshooting Information - Error Console output - profile file names/sizes/timestamps - Windows Event Viewer logs - sanitized prefs.js - comparison with a working fresh profile

Bugzilla report: 2081665 Known separate attachment bug: 2077590

This seems to have occurred in the last month or so.

Whenever I click on a message in the folders pane, the message is not displayed correctly in any of the three layout views but, if I am offered to display in a browser, it does! Also, if I select 'Edit as a new message' it displays correctly, as also do iPhone and iPads. The screenshot shows the problem?

Any ideas, anyone?

Hello, I am having an issue that Emails which are displayed in the reading area disapper for appr. 2 minutes. Afterwards they appear again. I have not been able to find out if this is a problem in Thunderbird, or if another application is causing this. I have read an article that Avast Antivirus is temporarily locking folders during scan. Maybe someone has had the same topic and can give me a hint where to search for the root cause. Thank you.

I am having constant problems for months now with Thunderbird freezing and message not responding. It appears to happen mostly when trying to empty deleted folder in block like 20 or more. If I deleted in blocks of four all is ok. As soon as I try to delete a larger amount at once it freezes and displays the message Thunderbird Not Responding. I have followed u tube videos to the letter to attempt repair with no success any ideas please?

Thunderbird (153.4.0esr (64-bit) ) does not display or let the user change its printer setting before launching print preview from the print command. If Thunderbird is set to choose a missing printer, it gets stuck trying to contact the missing device in order to prepare a print preview. It seems to be stuck forever, it does not seem to time out. There is no cancel button. If you close the document tab, you can permanently lose the document if it is a draft email, unless the email service saves it in a trash folder. The printer setting can be cleared if the user manages to learn how to display and clear the troubleshooting information.

Thunderbird needs to display the printer setting and permit the user to change it before launching the print preview operation. It needs to display a cancel button during the print preview operation.

I upgraded my system to Kubuntu 26.04 LTS and started Thunderbird. The window where messages are listed was covered with Thundrbird presentation asking for donation. Only edge of one message is seen above the presentation and I cannot get to the list

Lately, Thunderbird has been using excessive CPU time even when idle. I am on Windows 11 and running the 153.3.1esr release of Thunderbird. It's impacting other applications. When I exit Thunderbird, everything runs faster. Right now it's using over 7% CPU and about 500 MB of ram.

Hardware is HP Pavilion Desktop 590-p0xxx. Intel i5-8400 2.8 GHz 12 GB ram.