3432991 - Internal Error 505 "Failed to get execution sync for semahores[global= ; local=default]" in Synthetic User Monitoring

The SUM location/robot stops working from time to time and its assigned scripts report Internal Error 505 "Failed to get execution sync for semahores[global= ; local=default].

The agent.log of the robot contains more errors like:
WARN  [<FRUN SID>/<script>] com.sap.solman.agent.sum.lock.local.LocalLockManager semaphore default acquisition failed
java.lang.InterruptedException: null
WARN  [<FRUN SID>/<script>] com.sap.solman.agent.sum.lock.local.LocalLockManager semaphore default not acquired after waiting for 600 seconds
WARN  [<FRUN SID>/<script>] com.sap.solman.agent.sum.lock.LockManager a local semaphore cannot be acquired!
ERROR [<FRUN SID>/<script>] com.sap.frun.sum.core.executor.listener.ExecutionLogger reportInternalError(...)
com.sap.frun.sum.core.executor.sync.ExecutionSyncException: Failed to get execution sync for semahores[global= ; local=default] 

SAP Focused Run

KBA , SV-FRN-APP-SUM , FRUN: Synthetic User Monitoring (SUM) , Problem