Firefox "Error: couldn't send request"

[lars_al]

Hi

Had the same problem yesterday - found error message to pop up only if Firefox was opened when pc was offline.

In my case a new addon "Temporary Inbox" was trying to go online resulting in error massage.
With Temporary Inbox deactivated the annoyance was gone.

Maybe already you have found your own way out - otherwise deactivate all extension and activate one at a time to find the "sinner"