Using Dropbox with GAMS is NOT supported.

We suggest to run a GAMS job from a local hard drive directory, e.g. “C:\Users\aUser\Documents\gamsdir\projdir\myfirstGAMSproject”. We do NOT recommend to use a cloud service, like Dropbox, network drive or external drive, for a GAMS job.

Dropbox consists of cloud-based services and running GAMS from a Dropbox folder, may cause issues like:

*** Status: Terminated due to file open error in WRITE PARM
***         Inspect listing file for more information
---------------------------------------------
*** Unexpected Exception from eassertionfailed
*** Msg=Assertion Failed. (solve.c:3584) CerateAndPopulateDCTObject2.=Permission denied: 
---------------------------------------------
**** TERMINATED DUE TO A FILE OPEN ERROR IN 
**** PLEASE REPORT TO THE GAMS ADMINISTRATOR
---------------------------------------------
****GAMS Exit MSG=Invalid argument for file

The issue is caused when Dropbox has locked a file for synchronization and, simultaneously, GAMS tries to access the file. Furthermore, running GAMS from a Dropbox folder (or external drive) slows down the GAMS Job execution.

Be aware that, using a Dropbox folder during a GAMS job, may cause issues. However, if you insist on using Dropbox, then the following suggestions may be helpful. All files that are unchanged during a GAMS run, can be placed into a Dropbox folder. Use a local drive for temporary work files, created during a GAMS run, as well as, for GAMS output files. Note that, GAMS creates temporary work files in a temporary folder under the GAMS project folder, during a GAMS Job. If you are using the GAMSIDE, then you may do as follows:

1. Specify the GAMS project in a local directory.
2. Open the GAMS model from the Dropbox folder
3. Use command line option idir to instruct GAMS, to look for files, in the Dropbox folder, e.g idir=“C:\Users\Toni\Dropbox\gmsfiles”.

If you are using a Unix (Mac or Linux) machine, then you can run a model, let's say “/Users/aUser/Dropbox (Personal)/mymodel.gms” from a local folder that does Not contain white spaces, in the following way.

gams mymodel.gms idir=\"/Users/aUser/Dropbox\ (Personal)\"