Google Cloud Shell won't start; throws usage limits exceeded msg

I had same issue, the shell takes forever and stuck there. I simply clicked '+' (open a new tab).

A few seconds later, problems solved!

This has been resolved for me by Google; I had Cloud Shell sessions open for prolonged periods of time and had exceeded some fair-use limits set for it.

Anyone facing a lockout like this, please be sure to provide feedback as suggested by Alexey above.

Thanks once again, Alexey, for resetting the counters and re-enabling the console access...

I had a similar issue with with firefox where it hangs with 'Provisioning your Google Cloud Shell machine...'

Switched to google chrome and it got resolved.