Kinetic Functions Response Params and

Kinetic ERP
20

That’s not base 64 encoded. atob needs a base 64 encoded string. Looks like yours is already decoded. Do return a Byte Array from your function take the File and turn it into a byte array.

byte[] fileBytes = File.ReadAllBytes(strFile);
string base64EncodedString = Convert.ToBase64String(fileBytes);

Return taht.