Prior to running the ISE Design Suite 13.1 tools you must set up the environment.
This is done automatically via the settings32.bat and settings64.bat batch files that are located in the ISE_DS folder.
Each of these files will call the .settings32.bat or .settings64.bat files respectively that are located in each of the common, EDK, ISE, PlanAhead and SysGen folders to set up the environment for those tools.
These batch files in the SysGen folder are new to 13.1 and they include the lines:
set TEMP=C:\TEMPRegardless of what TEMP and TMP are set to that value will be overwritten by C:\TEMP when you run the settings32.bat or settings64.bat batch file.
To work around this issue change the above line to set the TEMP environment variable to whatever location you wish to use, for example:
Note: You must have read and write permissions to this location.
In ISE 14.1 the set script was changed so that the TEMP variable will only be set if it does not exist.
Also a %TEMP% folder will be created if it does not exist.