I can no longer install Apps

[metzlertoby]

I no longer have My add-on's. When I try to reinstall them I get a first error message,"Type error-button is null 30". Then I get a second message,"Exception... "Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getCharPref]" nsresult: "0x8000ffff (NS_ERROR_UNEXPECTED)" location: "JS frame :: resource://gre/modules/addons/XPIProvider.jsm -> jar:file:///C:/Users/Fred/AppData/Roaming/Thunderbird/Profiles/i6f7zbht.default/extensions/%7Bf69e22c7-bc50-414a-9269-0f5c344cd94c%7D.xpi!/bootstrap.js :: ThemeFontSizeChangerBootstrapAddon.getTFSCStyle :: line 1418" data: no]
1418T

I hve the same problem with 2 computers running windows 10 !

[WaltS48]

Apps? Do you mean extensions?

How are you trying to reinstall them?

Have you tried opening the Add-ons Manager clicking the Extensions tab, select the Gear wheel next to the Search Bar, then click "Check for Updates"?