I have tried printing a Global Freight Solutions (GFS) label and am seeing this error returned:
Error: 0040: FAILURE, Database error. I/O error during "CreateFile (open)" operation for file "C:\Program Files (x86)\GFS\Client\Database\GFS.FDB
This error is being returned because there is an issue on GFS end. Please contact Linnworks support if necessary to obtain the API request/response files which you can forward to GFS to investigate.