Please do not close the Package Manager window, or the Canopy Command Prompt / Canopy Terminal window, or the Preferences => Python => environment maintenance window, while installation or removal of a Python environment or package is happening in that window.
If an installation window is closed unexpectedly, two problems may occur:
a) Easy: All Canopy / embedded EDM environments may be left in a temporarily locked, inaccessible state. Beginning with Canopy 2.1.1, restarting Canopy will clear the lock and allow your work to continue.
b) Hard: Depending on what package operation is terminated unexpectedly, the environment might be left in a corrupted state, which could cause problems later.
In this case, the safest solution is to reset the Python environment. Resetting the default "User" environment can be most easily done from the Canopy Tools menu's Troubleshoot submenu. Other Python environments embedded in Canopy can be removed and recreated in the Preferences => Python dialog or by using Canopy's embedded edm utility at the command line (Tools menu => Canopy Command Prompt / Canopy Terminal).
If for whatever reason you don't want to reset the Python environment now, please do the following command at the Canopy Command Prompt / Canopy Terminal:
Then reinstall the affected package (if/when you know what package is missing) in EDM or in the Package Manager.
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