"Data Entity's Historical Data is out of sync!" Error Message in Perceive IGX Logs

Sometimes, you may see the following error message in your Perceive IGX Logs:

Extract <entity> Historical Data RUNNING ....
Data Entity <entity name>'s Historical Data is out of sync!

You can also see this in the UI -- a small red flag will appear for any field definitions that are our of sync:

This means that the Data Entity field definitions in Perceive don't match the related Assure control's field definitions. If Perceive doesn't need the new/modified fields, this message can be safely ignored. 

If not, you can synchronize the Historical Data by clicking the "Synchronize" button when editing the Data Entity (see screenshot below).