# Error Handling

When error happens, Reblocks either renders an error page or opens an interactive debugger.

Interactive debugger is opened only if server is running in debug mode. Also, in this mode, error page contains a backtrace.

If you want to customize how does error page look like, define a method for on-error generic-function.

This method is called when some unhandled error was raised by application. It should call reblocks/response:immediate-response like this:

(reblocks/response:immediate-response
"Unhandled condition"
:code 500)