All of a sudden I am not able to manually open a new tab. It was working fine until yesterday. I click on the "plus" and nothing happens.
Hello maxkufan, start firefox in Safe Mode and check it again, in Safe Mode window select "Start in Safe Mode" and see if this happen again, if not see: Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
if the above is unhelpful then see: Corrupt localstore.rdf, try the manual method.
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