Recently, we moved our Solution from Development to Test. Then on running one of the SSIS Packages we got the below error
The specified key attributes are not a defined key for the entity  CRM service call returned an error:
On opening the Entity for customization, and checking for the key, we saw that it was in the Status Pending.
On opening the system job, there was no detail for the error.
We normally get this error, if there are records already available that have duplicate values for that alternate key field. However, in this case, there we no record as this entity was being moved first time in the Test.
Well to just fix this we thought of manually reactivating the key
However, that threw a new error that “Reactivate entity key is only supported for failed job.”
To fix this go to Settings à System Jobs à search for the failed system job and delete them
Now we will see the status as Failed
This time it will allow running the reactivation.
Hope it helps..