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Article ID: 76 - Last Modified:

While working in Maestro, I get error messages in the terminal like:

WARNING : MMDBI ERROR(-4): mmproj_dbi_clear_undo(): Failed to clear the undo tables (database is locked)
WARNING : MMPROJ ERROR(-4): local_mmproj_prepare_db_for_potential_undo(): Failed to clear the undo

What does this mean?

These errors may indicate that a database in your project is locked, perhaps as a side effect of a sudden shutdown or power failure. To clear the lock, download the script and run it as follows:

$SCHRODINGER/run project_name.prj

When it finishes, try again to open your project in Maestro.

These errors can also appear when a project is stored on a shared file system such as NFS and file locking is not enabled. Moving the project to a local file system may help.

Proper file locking is necessary for Maestro projects, so the following locations:

/var/lib/nfs/sm (on SUSE Linux)


/var/lib/nfs/statd/sm (on RedHat Linux)

must be writable when NFS is used. The permissions have to be set properly (700) and the owner needs to be the same as the rpc.statd daemon.

To prevent problems with database locking, you can set the following environment variable to point to a local non-NFS location, which will be used for temporary storage of the database:


This should allow you to keep projects on a shared file system.

Keywords: sqlite, Linux

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