This error message indicates that you tried to use a work file (restart) file, which was most likely written by a newer version of GAMS (e.g. 148), by an older version of GAMS (e.g. 146).
The error message also pops up if a process is still writing to the work file while a second process tries to read the same file.
We make checks that certain sections in the work file are complete and because they were not complete you see this error message. Unfortunately, the message does not distinguish between an internal system error and a user error like using a newer restart file. In the future GAMS will issue a more informative error message.