When a file in a Template has been removed from the FileStore, following or similar error may occur when creating a Project from that Template (in 12.1.1):
com.eskographics.wc.ejb.WebCenterRemoteException: [UNKNOWNEXCEPTION_TAG] \\CSWCR1411\FileStore\documents\000017\e01d60d10a060a2201be494d631a7619.xml > Caused by: java.io.FileNotFoundException - \\CSWCR1411\FileStore\documents\000017\e01d60d10a060a2201be494d631a7619.xml
or in 14.1.1:
An unknown error occurred. Try your action again, if the problem persists contact your administrator. \\cswcr1411\FileStore\documents\000000\2e7fae3f0a1fe1321cfc4784c98bcdca.png
The file exists in the database and is not seen as deleted, however when checking the FileStore it has been removed.
To resolve the issue, delete the file from the Template and upload it again to restore the situation.