A CHECKOUT LIBVOLUME command cannot find an empty and available entry/exit port to place the volume to be removed.
The server waits until the operator performs the actions requested.
Make at least one entry/exit port empty and accessible. Check the entry/exit ports or the library. Make sure the entry/exit door is closed. If all the entry/exit ports are full remove at least one volume from the entry/exit port. If any of entry/exit are empty then the empty entry/exit ports are inaccessible. Check the library's documentation on how to make the entry/exit port accessible. If the library is incorrectly reporting the status of the entry/exit port contact the library vendor.