diff --git a/docs/known-issues.md b/docs/known-issues.md
index a35b104d49c966d94221a3d3e3c79f012633c2c9..408a729ed19454c9217196afde18ecfd0f65e1b7 100644
--- a/docs/known-issues.md
+++ b/docs/known-issues.md
@@ -58,6 +58,26 @@ The maximum allowed file size for uploads is currently set to 2.5MB.
 
 Ensure that the file size is under 2.5MB before attempting to upload it.
 
+## Exercise cannot be started after 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.