Javascript error when starting Firefox 5
I've just upgraded Firefox from 4.0.1 to 5. Now when I start Firefox, the following error message appears:
JavaScript Application TypeError: Components.classes[cid] is undefined
When I click the OK button, Firefox loads. It looks normal, and seems to behave normally. I have Java Version 6 Update 26 installed (Windows XP), which is the latest version.
Seems to be a Firefox problem, as I didn't have it before with the same version of Java installed. Is there a Firefox setting that needs to be changed, or is it maybe a Firefox bug?
Solution choisie
Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).
- Don't make any changes on the Safe mode start window.
- https://support.mozilla.com/kb/Safe+Mode
If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.
- Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
- Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")
In Firefox 4 you can use one of these to start in Safe mode:
- Help > Restart with Add-ons Disabled
- Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)
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Solution choisie
Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).
- Don't make any changes on the Safe mode start window.
- https://support.mozilla.com/kb/Safe+Mode
If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.
- Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
- Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")
In Firefox 4 you can use one of these to start in Safe mode:
- Help > Restart with Add-ons Disabled
- Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)
Thank you. The problem appears to have been with the theme "Firefox 3 Theme for Firefox 4+." After switching to the default theme, "Default 5.0," the JavaScript error doesn't appear.