This is an old revision of the document!
Version 22.3 of GAMS introduced a new format (version 6) to store gdx files in a compressed form with some significant savings both in file size and writing time. However we were forced to break backwards compatibility. We were loathe to do this but we couldn't introduce compression without doing so.
Thus prior versions used version 5 and can not read the format of version 6. If this is the case you will get an error:
c:\test\gdx2veda test *** Could not open GDX: test.gdx *** Msg: File version not supported c:\test\>
Solution: Use the utility
gdxcopy to convert from the newer file format to an older one. This utility is part of current distributions.
If you are not sure which version of GAMS has been used to create that gdx file, use the tool
gdxdump to inspect the contents of your gdx file. The
File version part is what you can pay particular
File version : _GAMS_GDX_235_2005-11-15
File version : _GAMS_GDX_237_2007-01-09