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Why does Firefox keep opening in a tiny window?

  • 3 replies
  • 1 has this problem
  • 16 views
  • Last reply by FredMcD

Firefox frequently - but not always - opens in a tiny window - which then has to be stretched to the full-window size it was until closed. Has started with this version: 91.0.2 (64-bit)

Thank you for your help.

Firefox frequently - but not always - opens in a tiny window - which then has to be stretched to the full-window size it was until closed. Has started with this version: 91.0.2 (64-bit) Thank you for your help.
Attached screenshots

Chosen solution

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?


https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved You may have corrupt xulstore.json file.

Close Firefox. Open your file browser to this hidden location:

  • Mac: *~/Library/Application Support/Firefox/Profiles
  • Linux: *~/.mozilla/firefox/Profiles
  • Windows: %AppData%\Mozilla\Firefox\Profiles
  • *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles
  • Windows XP: C:\Documents and Settings\<user>\Application Data \Mozilla\Firefox\Profiles\

Search for the above file. Then rename or delete it. Restart Firefox.

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All Replies (3)

Chosen Solution

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?


https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved You may have corrupt xulstore.json file.

Close Firefox. Open your file browser to this hidden location:

  • Mac: *~/Library/Application Support/Firefox/Profiles
  • Linux: *~/.mozilla/firefox/Profiles
  • Windows: %AppData%\Mozilla\Firefox\Profiles
  • *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles
  • Windows XP: C:\Documents and Settings\<user>\Application Data \Mozilla\Firefox\Profiles\

Search for the above file. Then rename or delete it. Restart Firefox.

Hi. Thank you for your prompt - and very helpful - answer! That has fixed it. And I now know where to look to fix similar problems. Thanks again for your help.

Glad to help. Safe Surfing.