Can not remove folder from library

I have added a network source containing the same content as a local resource. Now I want to remove the local resource from the library, but get "An unexpected error occurred (500). Check the log.". The same message appears if I try to change the content of the library to hide it.
I have tried to stop and start the Serviio server, service and console. The folder/files are still present (not deleted).
I can not find out what the source of the error is from the log file. Log file attached.
I can remove or change other entries in the Library Folder List
I am running Serviio PRO 1.3.1, Windows Home Server 2011
I have tried to stop and start the Serviio server, service and console. The folder/files are still present (not deleted).
I can not find out what the source of the error is from the log file. Log file attached.
I can remove or change other entries in the Library Folder List
I am running Serviio PRO 1.3.1, Windows Home Server 2011