When using file cabinet synchronization in DocuWare, errors can occur if the DocuWare versions on the involved servers are not the same. One of the possible errors is:

“Synchronization job was aborted due to an error. Look into the job summary. 400 Bad request (The content type header is missing. Cannot deserialize the request body.)”

This error can occur when the DocuWare versions on the synchronized servers are different. File cabinet synchronization requires that all involved servers use the same version of DocuWare. Otherwise, conflicts in communication between the servers can occur, resulting in errors.
To ensure that file cabinet synchronization in DocuWare works smoothly, you must ensure that all involved servers use the same version of DocuWare. If you install a new version of DocuWare, make sure all involved servers are updated to the new version before starting file cabinet synchronization.
If the error has already occurred, you need to investigate the cause of the error by checking the synchronization log. The log typically indicates which server is using the wrong version of DocuWare. Make sure this server is updated to the same version as the other servers. Then, run file cabinet synchronization again to ensure the problem is resolved.
If you are using the synchronization between DocuWare Cloud and on-premise, both systems must use the same version.
In some cases, it may also be helpful to reconfigure file cabinet synchronization to ensure that all settings are correct. Check the settings on all involved servers and make sure they are correct.