Knowledge Base

When Maestro starts, I get an error message "No module named core". What do I do?

The full error message is:

ImportError: No module named core ...
ImportError: numpy.core.multiarray failed to import

The error may arise if PYTHONPATH is set to a location other than the one in the Schrödinger software installation. One option is to unset the PYTHONPATH variable before starting Maestro. Another is to set the SCHRODINGER_PYTHONPATH variable to a string that contains a single space character. See Article 1842 for information on setting environment variables. For example, on Linux enter the following command in a terminal window:

csh/tcsh: setenv SCHRODINGER_PYTHONPATH " "
bash/ksh: export SCHRODINGER_PYTHONPATH=" "

If Maestro still does not start, you may have a conflicting library in a user site-packages library. On Linux or Mac OS X, this is ~/.local/lib/pythonX.Y/site-packages and on Windows it is %APPDATA%/Python/PythonXY/site-packages, where X and Y are version numbers.

To fix it, you can set the environment variable PYTHONNOUSERSITE to a string that contains a single space character, to exclude this location as well. For example, on Linux:

csh/tcsh: setenv PYTHONNOUSERSITE " "
bash/ksh: export PYTHONNOUSERSITE=" "

If this does not permit Maestro to launch, please contact Technical Support.

If you are running an old release, issues like this can also arise when there is more than one Schrodinger suite installed in a single $SCHRODINGER directory. This practice is no longer permitted.

To ask a question or get help, please submit a support ticket or email us at

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