Seems to be a larger error in Version 35.0. We have the problem in all instances installed in the office and the whole family had.
The trouble here is:

• the Auto-Updater is not to disable easy

• old versions of Opera you can not download, at least I have not found a link to the old versions (V34.0?)

My solution was:

• from a Time Machine backup Opera in version 34.0 from Feb 1 recovered

• in the folder "Opera.app/Contents/MacOS" I delete "opera_autoupdate", "opera_updateinstaller", "opera_crashinspector", "opera_crashreporter" (The first two are required, the last two according to your mood.)

Feature request to Opera ASA:

• turn off setting to the auto-update-service

• version history of all the old versions to download, if there should be this somewhere = >> clearly inform about

Until then, I recommend everyone to turn off the auto-updater, regardless of which way, and every 3-4 months, according to examine current bug-reports, manually update or use FF.