# Known Issues and Fixes

This page outlines the known issues associated with the platform and provides guidance on how to resolve or work around them.

## Exercise cannot be started after an outage

### Issue

Cannot start an exercise even though all exercises are stopped.

### Cause

When an exercise is running, a special lockfile is created.
This lockfile is deleted automatically when the exercise is stopped.
If the backend server crashes or the server is manually stopped during a running exercise,
this file will not be properly deleted, preventing from starting this specific exercise again.
The server is set up to automatically delete all lockfiles on startup.
However, if this issue persists even after restarting the server,
it could be possible that the process failed.
Ensure that no lockfiles are present in the `data` directory with the name `exercise-<ID>.lock`.
The `data` directory is located in the base directory of the backend.
These files can be deleted while the server is running,
however only if there are no actual running exercises.

## Conclusion

If you require further assistance, don't hesitate to report issues to us. The [Report issue](report-issue.md) page includes instructions on how to report bugs.
