Firefox crashed - Cant add LastPass

Recently Firefox crashed and would not open a message asking me to ‘Refresh Firefox’ appeared.

I tried several times to refresh Firefox but it would not open. I then removed and reinstalled Firefox, I then rebooted the machine and Firefox could then be opened.

Why did this happen?

I then noticed that LastPass was not in my extensions for Firefox I tried adding it several times each time a message appeared “Download failed. Please check your connection”.

What is happening here?