When something fails.
THE FIRST STEP
Read the application log.
It usually states the cause precisely.
APPLICATION WILL NOT START
Syntax error Missing dependency Missing environment variable Wrong startup file or entry point
Each is named in the log.
APPLICATION STARTS BUT RETURNS AN ERROR
A failure handling the request.
The log shows the traceback.
CHANGES NOT TAKING EFFECT
The application was not restarted.
The most common report of all.
DEPENDENCY WILL NOT INSTALL
It may require compilation or system packages.
Try an alternative, or ask.
APPLICATION RESTARTS UNEXPECTEDLY
Usually memory. Check resource usage.
WORKS LOCALLY, FAILS ON THE SERVER
Different Python version Different dependency versions Missing environment variable A path assumption A file not deployed
WHAT TO CHECK IN THAT CASE
Versions first, then configuration, then paths.
WHAT TO INCLUDE IN A TICKET
The application URL, the exact error from the log, and what you have checked.
