Avast blocking Twitter

Avast just updated virus definitions on my machine (running Windows 7 Pro, Firefox browser) and now Twitter is blocked by a popup warning. It isn’t the standard threat warning but just says that ‘The site could have harmed your computer.’ No details as to why. Adding Twitter’s URL to the exclusion list doesn’t work. Any idea what to do? No other https sites appear to be blocked.

Program: 18.6.2349 (build 18.6.3983.0)
Virus definitions: 180831-4

PS Twitter accessible via Internet Explorer… But not via Firefox.

Same issue with the popup from the avast online security extension blocking any twitter links saying it may have harmed your pc. Only way I can stop it is by turning the extension off in the browser settings, but that’s not really a solution I’d advise. I tried excluding twitter on the web shield settings but that didn’t fix it at all.

Using Google Chrome and all my programs are up to date, hopefully avast can hotfix the problem soon.

The Avast team are working on it now.

This has been reported and the Avast team is working on a fix.

This false alarm was fixed. Sorry for any inconvenience.

Thank you!