Swagger UI not allowing upload of text files.

Hello!

I was trying to upload two **.txt** files to do some text processing. I uploaded through the input fields in Swagger UI generated by API. But, the Swagger-UI gives me the following error:
Details


Here's the relevant parts of the code:
```python
class HeaderSchema(ma.Schema):
id = ma.fields.String()

class MultiFileSchema(ma.Schema):
prev_file = Upload(format='binary')
post_file = Upload(format='binary')

class FormSchema(ma.Schema):
type = ma.fields.String()

@blp.route("/result-file")
class ResultFile(MethodView):
@blp.arguments(HeaderSchema, location='headers')
@blp.arguments(MultiFileSchema, location='files')
@blp.arguments(FormSchema, location='form')
@blp.response(200)
def post(self, header_args = None, files_data = None, form_data = None ):
.
.
.
```
The code works fine when tested using Postman. Problem only shows up in Swagger-UI

Also, when I didn't attach the files in the Swagger-ui, the code worked fine and returned intended response, so **likely the issue might be with the Upload() field.**

What could I be doing wrong?

Thanks!

Start by reproducing the /result-file endpoint in Swagger UI with two .txt uploads, then compare the generated request with the working Postman request. Inspect the generated OpenAPI form schema and Upload fields; done means text files can be selected and submitted successfully through Swagger UI while the existing endpoint behavior remains intact.

Written by the indexing model from the issue text.