When executing a Business Central map that gets this error.
Step 1 is to check the Business Central connection by verifying with the Microsoft Azure account. Ensure your client credentials and App settings are set correctly as shown in the article below.
Step 2 is to investigate the data in the group by records does not include the # character. For Example: for the Item, the item code should not include the # character.
Business Central rejects the # character in the Group by key fields, which leads to this error.