What information should I gather before opening an Azure support ticket?

Having the following ready generally speeds up resolution significantly:

Useful information to prepare

• The affected resource name(s) and resource group
• Approximate time the issue started
• Any error messages, error codes, or screenshots
• What you were trying to do when the issue occurred
• Whether the issue is intermittent or consistently reproducible

Providing this upfront (rather than a general "it's broken" description) usually leads to much faster diagnosis, whether you're working with your CSP partner or Microsoft directly.