The complete error message in the log file was:
*** *** Workfile with 1 execution errors(s) *** To clear this condition use the GAMS parameter FORCEWORK=1 or FW=1. *** All unexecuted code will be flushed. *** *** Status: Execution error(s)
You get this error message, if the run which generated the restart file terminated with an execution error. Please inspect the lst file of that run for further information, what triggered that error message. An example for such an execution error is
Exec Error at line 19965: rPower: FUNC DOMAIN: x**y, x < 0.
If this happens GAMS will still generate the save file. However to make sure that you are aware of the potential problems with the save file you will get the error message above. If you insist on using it with these error messages, you have to add the GAMS parameter FORCEWORK=1 or FW=1 to your command line.