We frequently get above error during data load in Essbase using Rule files and Maxl scripts. The reason for it is Essbase encountered a field in the data source that it did not recognize. Most comman reason we encountered for this error is a new value ( eg. Customer, Product etc.) is added on the source side which doesn’t exists in the Essbase cube stored members.
To fix this error, look at the log files and identify the missing Item/member and add it to the Essbase cube outline.