When updating add-ons I frequently get Download error -228 for all updates. Trying again later, they all update successfully.
When Firefox starts up it checks for add-on updates. Frequently I get "Firefox could not install the file at http://releases.mozilla.org/pub/mozilla.org/addons/10868/forefox_sync-1.6.3-sm+fb+fx.xpi because Download error -228" This one is for Firefox Sync; I get equivalent for any others for which updates were found. I find all updates will apply, or none. It's never some do and some don't.
Alla svar (2)
See if this helps you,
https://support.mozilla.com/en-US/kb/unable+to+install+add-ons#Download_Error_228
Thanks for the link. Unfortunately this doesn't help because without changing any setting the update will eventually install be it a day or three later. .. If updates were disabled, then they would remain disabled and no updates would ever install (& I'd expect a more relevant worded message), which is not the case. I would expect Firefox to find updates to extensions only if they were compatible, or again tell me "not compatible" rather than a nondescript "download error" message. .. I have Firefox auto-updating so am on the latest release (not beta) most of the time .. until it tells me to download the latest.