E2121 Invalid Query Filter Operator

When querying data from Salesforce, this error message INVALID_QUERY_FILTER_OPERATOR will be displayed in the following scenarios:

A. When the query contains an incorrect filter operator for the data type of the field being queried. For example, you have set up a filter on your transfer so you select only the following records: SELECT Id FROM Account WHERE Name > 'Acme Corp'. However,the "Name" field is a text field, but the query is using the > (greater than) operator, which is not valid for text fields.Text fields should be compared using operators like = (equals) or LIKE. 

How to Fix It:

• Use correct operators based on the field type: 
  • Text fields → =, LIKE
  • Number fields → >, <, >=, <=, =
  • Date fields → >, <, =, BETWEEN
• Check Salesforce’s documentation to see which operators are valid for each data type.

B. When the query contains incorrect data and Salesforce is not able to run it correctly. For example:

E2121 - ECE_SOAPFaultResponse: We received a SOAPFault response from the server:FaultCode: Client
String.....: INVALID_QUERY_FILTER_OPERATOR: WHERE Customer_Number__c = '' AND Legal_Entity__c = 'ABC'^ ERROR at Row:1:Column:200
invalid ID field: ABC detail: [UnexpectedErrorFault: Attributes: type = "sf:UnexpectedErrorFault" [exceptionCode: INVALID_QUERY_FILTER_OPERATOR , exceptionMessage: WHERE Customer_Number__c = '' AND Legal_Entity__c = 'ABC'^.

How to Fix it:

• If Customer_Number__c is a number field, you cannot compare it to an empty string (''). Therefore, the query should be WHERE Customer_Number__c = NULL.
• 'ABC' is not a valid format, so Salesforce throws an error. So it needs to be checked directly in Salesforce and make sure that the field itself displays 'ABC' as an option for the Legal entity.