MDS Error: “200085: The attribute cannot be saved. The input mask is not valid.”

During a recent deployment, I received an error that I’d never seen before. It’s always fun to get these.

“200085: The attribute cannot be saved. The input mask is not valid.”

My initial thought was that someone had modified an attribute and created a conflict. The model was new and sparsely populated, so I was able to view the data. It didn’t appear to be data related.

It turned out to be a custom input mask was not included in the deployment. The mask was created in a lower environment but never migrated. Once that update was made the deployment completed successfully.