dotnet/aspnetcore

HttpRequest.Form throws an undocumented System.InvalidOperationException

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#49096 opened on Jun 29, 2023

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Description

Is there an existing issue for this?

  • I have searched the existing issues

Describe the bug

After upgrading from ASP.NET Core 3.x to ASP.NET Core 6, we found that HttpRequest.Form throws an undocumented System.InvalidOperationException with the message "Incorrect Content-Type: image/png".

System.InvalidOperationException: Incorrect Content-Type: image/png
   at Microsoft.AspNetCore.Http.Features.FormFeature.ReadForm()
   at Microsoft.AspNetCore.Http.DefaultHttpRequest.get_Form()

This seems to only affect image files. Using the same code to read CSV files continues to work.

Expected Behavior

Form object is returned.

Steps To Reproduce

No response

Exceptions (if any)

System.InvalidOperationException

.NET Version

7.0.304

Anything else?

Contributor guide

Tech stack
csharp
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
ASP.NET Core basicsHTTP knowledge
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55
Research direction
The issue points to the FormFeature.ReadForm() method in the ASP.NET Core source code (likely Microsoft.AspNetCore.Http.Features.FormFeature). The error occurs when the content type is not a form type (e.g., image/png). Investigate the content type validation logic there and consider whether the exception message should be improved or the form read should be allowed for non form content types. Also, review the linked documentation for HttpRequest.Form to see if the exception is now expected behavior.