Error message "compound primary keys are configured, but this nodeId is not a valid compound key"

[sfpx]

What causes this message ?

[Jesse Barnum]

It means that the table is configured in the MirrorSync configuration client with two primary keys instead of one, but when it's reading from the database, it's only getting one primary key value. This might be caused with a join table if one of the foreign keys are blank. If you didn't intend to have two primary keys (really only applicable for join tables), go into the configuration and remove one of them.