MSI (s) (40:E0) [18:35:46:882]: Note: 1: 1722 2: install_script 3: C:\Python26\\python.exe 4: C:\Python26\Scripts\foo-install-script.py
This means: There is a problem with this Windows Installer package. A program run as part of the setup did not finish as expected. Contact your support personnel or package vendor. Action [2], location: [3], command: [4]
MSI (s) (40:E0) [18:35:50:978]: Note: 1: 2262 2: Error 3: -2147287038
This means: Stream does not exist: [2]. System error: [3].
What does "The control ErrorIcon was not found on dialog ErrorDlg" mean?
It probably means it couldn't post the error message for the first error, because the icon to indicate "error" isn't included in the MSI file (which is a separate bug).
What's a postinstall script supposed to return or exit with to indicate success or failure, anyway?
It should return 0 as the exit code.
Any ideas?
I can think of two reasons: a) it may dislike the double-backslash in the Python path. Try removing one of them b) the command line may need to repeat the executable name as argv0. I would use orca (from the platform SDK) to edit the MSI file, and see whether this fixes anything. Regards, Martin