Sorry, the Add-ons team is working on a fix for this. It looks like a certificate used to sign many popular extensions expired. (The verification process checks that certificate.)

I don't know how soon re-signed versions of those extensions will become available, or whether another workaround will be discovered. We are all hoping to learn more soon.

Thanks! Can't say I haven't let a critical certificate expire before; they kind of become invisible until they hop out at you all at once one fine day.

I have JUST had this on my Laptop (desktop OK so far). I see that it is an ADD-IN Certificate issue (for developers to use), and that the ADD-ONS team is working on it.

NOTE: To the OP (silverbacknet) - it is NOT one of your local Root or other (SSL type of thing) certificates, it is the signing certification process, used by the DEVELOPERS of the add-ins in question, that has gone wrong, so it is WRONLGY flagging the add-ins as bad and un-signed, and some autom,atic process is disabling them!! Hopefully this will be fixed ASAP, otherwise I can see that many users will switch to CHROME, and might not all come back.

I should have come here and looked for this issue before spending a half hour collecting info and times and putting together a detailed post...LOL.

I hope a fix comes soon... AdBlock, uBlock and Avast Online Security are just three of the add-ons I have that were affected. I dunno if life is worth living online without AdBlock!

Thanks jsher2000 & td47 for the info.