Dataflow fails with error "contains invalid characters. ",;{}()\n\t=" are not supported"

[DataSkills]

Hello, I have a dataflow that is causing errors. 

The full error message is:

JT_TASK_WriteToDataDestination: There was a problem refreshing the dataflow: 'Couldn't refresh the entity because of an issue with the mashup document MashupException.Error: DataSource.Error: Pipeline execution failed (runId: xxxxx-e36c-47ae-9377-9f5669aa9514). Operation on target ca-xxxxxx-0c53-4098-a285-519620e6cc83 failed: Failure happened on 'destination' side. ErrorCode=DeltaInvalidCharacterInColumnName,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Column name Work Task No contains invalid characters. ",;{}()\n\t=" are not supported.,Source=Microsoft.DataTransfer.ClientLibrary,' Details: Reason = DataSource.Error;RunId = xxxxx-e36c-47ae-9377-9f5669aa9514'. Error code: Fast Copy User Error. (Request ID: xxxxxxx-06c1-4bd6-9513-87bee9df9bf4).

The code where the column names are modified is as follows:

Table.RenameColumns(#"Removed other columns", {{"TASK_SEQ", "Work Task No"}, {"WO_NO","WO No"}, {"SITE","WT Site"}, {"ORGANIZATION_SITE","Maint Org Site"}, {"ORGANIZATION_ID","Maint Org"}, {"WORK_TYPE_ID","WT Work Type ID"}, {"DESCRIPTION","Description"}, {"LONG_DESCRIPTION","Long Description"}, {"CREATED_BY","Task Created By"}, {"CREATED_DATE","WT Created Date"}, {"PREPARED_BY","Prepared By"}, {"REPORTED_BY","Reported By"}, {"REPORTED_DATE","Work Task Reported Date"}, {"ACTUAL_START","WT Start Date"}, {"ACTUAL_FINISH","WT Finish Date"}, {"SLA_LATEST_FINISH","SLA Date"}, {"EXCLUDE_FROM_SCHEDULING","Excluded from Scheduling"}, {"EXCLUDE_FROM_SCHEDULING_DB","Exclude from Scheduling"}, {"ADJUSTED_DURATION","Adjusted Duration"}, {"REMARK","Remark"}, {"INTERNAL_REMARK","Internal Remark"}, {"ACTION_TAKEN","Action Taken"}, {"CANCEL_CAUSE","Cancel Cause"}, {"ERROR_CAUSE_LONG","Error Cause Long"}, {"ERROR_TYPE","Error Type"}, {"ERROR_CLASS","Error Class"}, {"ERROR_DISCOVER_CODE","Error Discovery Code"}, {"ERROR_SYMPTOM","Error Symptom"}, {"ITEM_CLASS_ID","Item Class ID"}, {"ERROR_CAUSE","Error Cause"}, {"FAILING_COMPONENT","Failing Component"}, {"PERFORMED_ACTION_ID","Performed Action ID"}, {"PERFORMED_WORK","Performed Work"}, {"VENDOR_NO","Supplier No"}, {"CONTACT","Contact"}, {"CONTACT_PHONE_NO","Contact Phone No"}, {"E_MAIL","Email"}, {"SOURCE_REF1","Source Reference"}, {"CHANGED_DATE","Changed Date"}, {"C_ORIGIN_WORK_TASK","Original Work Task"}, {"C_COPIED_REVISIT_TASK","Copied Revisit Task"}, {"C_FUNCTIONAL_SITE","Functional Site"}, {"STATE","WT Status"}, {"OBJKEY","Task OBJKEY"}})

The error message appears to suggest that it's that very first column "Work Task No" which has invalid characters. I don't know WHY it's saying that as there are no invalid characters. I have this identical name being used elsewhere in my lakehouse. This is really frustrating me. Can anyone suggest what I have overlooked? 

Thanks in advance. 

[DataSkills · Accepted solution]

In follow up to my previous message, I have managed to overcome this frustrating issue.

I want to mention that I had already tried dropping the Lakehouse destination table, which didn't resolve the issue. I had also attempted to delete and recreate the destination on the dataflow query, without success. 

I then went the route of recreating the query from scratch, literally duplicating the steps one by one, and THEN I set up the data destination. Once I had a duplicate query, I deleted the original query (in the dataflow) and republished and it finally worked. 

These kinds of issues are frustrating, as they reveal Fabric's soft underbelly! But a lesson to me (and possibly to others) is, when in doubt, try starting from a clean slate.