Forum Response - Troubleshooting Thunderbird using Throubleshoot Mode

To diagnose problems with Thunderbird, try one of the following:

• Restart Thunderbird with add-ons disabled (Troubleshoot Mode Thunderbird). On the Help menu, click on "Troubleshoot Mode" - do not use the checkbox to permanently disable add-ons. If Thunderbird behaves properly, an add-on or theme may be interfering with normal operations. To test:
  • Restart Thunderbird and test add-ons by disabling all of them, then re-enable one at a time until you locate the offender. (Or if you have many add-ons, try disabling half at a time.)
  • Test themes by trying other themes.

If the above doesn't fix the problem, a setting or user customization could be interfering.

• Restart the operating system in safe mode with networking enabled. This loads only the basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 11, Windows 10, Windows 8, Windows 7, OSX. (General information about safe mode with Networking.)

If safe mode for the operating system fixes the issue, then software loaded during computer startup is causing problems. Possibilities include but are not limited to: AV scanning, virus/malware, background downloads such as program updates.

• If the problem is a performance issue, follow the steps in Profiling Thunderbird Performance and provide us with a URL to a performance profile.