Official comment
Hi Dhanashri,
As I can see in the screenshot and in our logs the specified URL is as following:
/V2.0/services/data/entityQuery?typeName=Customer&fields=SYSID,Name,Description,CreatedBy,CreatedOn,C_BusinessLeader,C_ParentCustomer,LastUpdatedBy,LastUpdatedOn&paging= {"from": 0,"limit": 25}&where={ "and": [ { " leftExpression":{ "fieldName": "SYSID"}, operator: "Equal", "rightExpression": {"value": "C-204" } }
The "where" condition is not closed properly. You did not close the "and" with a bracket and the "where" with the brace.
In addition you have extra leading space in " leftExpression" property name.
Note: you do not need to use "and" when you have single condition.