API ERROR: Invalid base64-encoded string: number of data characters (5) cannot be 1 more than a multiole of 4

[dbodbo]

I'm getting this error when trying to run via api, does anyone know how I can fix it?
I'm generating base64 through this website:

{ "error": "Error", "detail": " ", "body": " ", "errors": "Invalid base64-encoded string: number of data characters (5) cannot be 1 more than a multiole of 4" }