This work for me. Go to your profile folder (My is for example here C:\Users\Ohaha\AppData\Roaming\Opera Software\Opera Stable)

Delete files:
History
History Provider Cache
History-journal
Restart Opera.

This work for me. Go to your profile folder (My is for example here C:\Users\Ohaha\AppData\Roaming\Opera Software\Opera Stable)

Delete files:
History
History Provider Cache
History-journal
Restart Opera.

@ljfried Same, 1-2 hours worked fine, but later launched and got a blank page.