000511 : Unable to get a schema lock for <value>.

Description

To modify the alias of a feature class, the Set CAD Alias tool has to create a schema lock so that it can modify the alias of the field. If the tool cannot acquire a schema lock to allow editing of the field, this error surfaces.

Solution

Another user or application has created a schema lock which prevents the tool from getting one. Close the other application pointing to the feature class or check if another user is accessing the data.