7-5-12. Timeout error occurs

Q.

Timeout error occurs.

A. 

If deployment takes certain amount of time, timeout error may occur. If deployment takes more than 900 seconds (15 minutes), SkyVisualEditor automatically alerts timeout.
Even if a message is shown in the Studio saying timeout error is occurring, processes such as Apex test execution should be running in Salesforce. Please check if deployment was successfully done a little later.
You can check the status of deployment in "Monitor Release".
Setup -> Application -> Release -> Monitor Release