when export data to excel error excel file not readable content?

problem

I work on angular 7 app I click button to export data from database to Excel it create file when i open it

give me error ( excel file not readable content ) why and how to solve issue this my problem .

I pass parameter value to stored procedure and execute it and get result from database then export it to excel .

Exec exec dbo.getRevision 19253747
Main issue why not export data to excel and how to make export correct this actually what i need .

web API asp.net core 2.2

[HttpPost]

public IActionResult GetDataBasedOnDynamicSp([FromBody] dynamic DataObjectRevision)
{

string SpName = DataObjectRevision[0].downLoadProcedureName;

string revid = DataObjectRevision[0].revisionID;
var PostRevision = _reportservice.GetSpByRevisionId(revid, SpName);

return Ok(PostRevision);



}

Angular service.ts

GetSpByRevisionId(datarevision : any){
return this.http.post<any>('http://localhost:61265/api/report',datarevision)

}

component.ts

public exportJsonAsExcelFile(json: any[], excelFileName: string): void {
const worksheet: XLSX.WorkSheet = XLSX.utils.json_to_sheet(json);
const workbook: XLSX.WorkBook = { Sheets: { 'data': worksheet }, SheetNames: ['data'] };
const excelBuffer: any = XLSX.write(workbook, { bookType: 'xlsx', type: 'array' });
this.saveAsExcelFile(excelBuffer, excelFileName);
}
private saveAsExcelFile(buffer: any, fileName: string): void {
const data: Blob = new Blob([buffer], { type: EXCEL_TYPE });
FileSaver.saveAs(data, fileName + new Date().getTime() + EXCEL_EXTENSION);
}
getDataByRevision(RevId : any)
{

this.ReportData.forEach(function(e) { e.revisionID=RevId });
this._displayreport.GetSpByRevisionId(this.ReportData).subscribe(data=>{
console.log(data)
this.exportJsonAsExcelFile(this.ReportData ,'datarevision');
});


}

component .html

<td> <button (click)="getDataByRevision(rep[0])">Download</button> </td>

Data below is result of API and angular above and this data Exactly must show on Excel But this Not Done

(3) [{…}, {…}, {…}]
0: {revisionid: 19253747, revisionname: "parts", revisioncity: "usa"}
1: {revisionid: 19253747, revisionname: "company", revisioncity: "russia"}
2: {revisionid: 19253747, revisionname: "family", revisioncity: "german"}
length: 3
__proto__: Array(0)