Troubleshooting guides
Plain-text troubleshooting guides for software error codes and enterprise systems: Windows, Microsoft 365, databases, Kubernetes, identity, and web servers.
- SQLSTATE 28000
How to Fix PostgreSQL Error Code 28000 (Invalid Authorization Specification)
PostgreSQL SQLSTATE 28000 indicates an authorization-related connection failure, commonly caused by an incorrect pg_hba.conf rule, a missing or misconfigured database role, or a mismatch with the server authentication configuration.
· Databases
- 0x80070005
Fix Windows Update error 0x80070005 (Access Denied)
Windows Update fails with 0x80070005 when the update agent cannot write to its own folders or registry keys. Reset permissions, clear the cache, and retry.
· Windows
- Error 18456
SQL Server error 18456: Login failed for user
Error 18456 is deliberately vague on the client. The state number in the SQL Server error log tells you the real cause — here is how to read it and fix each one.
· Databases
- CrashLoopBackOff
Kubernetes CrashLoopBackOff: a step-by-step diagnosis
CrashLoopBackOff is not an error in itself — it means a container keeps exiting and kubelet is backing off. Find the exit code, read the previous logs, and fix the cause.
· Kubernetes
- AADSTS50076
AADSTS50076: MFA required — fixing service and legacy sign-ins
Microsoft Entra ID returns AADSTS50076 when a sign-in needs multifactor authentication but the client cannot prompt for it. Common with scripts, legacy auth, and service accounts.
· Identity, Microsoft 365
- HTTP 502
Nginx 502 Bad Gateway: upstream errors decoded
A 502 from Nginx means the proxy reached out to your app and got nothing usable back. The Nginx error log names the cause in one line — here is what each line means.
· Web Servers
- 0x800CCC0E
Outlook error 0x800CCC0E: cannot connect to server
Outlook reports 0x800CCC0E when it cannot open a connection to the mail server. Usually a wrong port, blocked TLS, or a firewall — rarely Outlook itself.
· Microsoft 365