Diagnose common failures methodically.

Admin returns to login

• Confirm the browser sends KBILLINGSESSID.
• Clear site cookies once after changing session configuration.
• Check PHP session storage permissions and shared storage across web nodes.
• Do not mix HTTP and HTTPS.

Database at capacity

• Check connection limits, slow queries and long transactions.
• Confirm cron is not overlapping and rate limiting is enabled.
• Use Database Status and slow-query logs; do not blindly add indexes.

Email

• Send a test and inspect Mail Queue error codes.
• Verify host, port, TLS, credentials and sender domain.
• Do not disable TLS peer verification.

Modules

• Run Test Connection.
• Confirm product/server/package mapping.
• Inspect order and automation events.
• Correct the cause before retrying.