mediaType null or empty when using RestSharp 108.0.2 with .NET 7

[cheindel]

Describe the bug

After changing target framework from .NET 6 to .NET 7 the following code in a Blazor server side application started to throw an exception (no matter if individual packages are referenced using their 6.0.10 or 7.0.0 versions):

var request = new RestRequest(BaseUrl + "waitinglist/" + accessToken);
request.AddParameter("officeNumber", PracticeId);
request.AlwaysMultipartFormData = true;
request.Method = Method.Post;
var response = client.ExecuteAsync(request);

Once I change target framework back to .NET 6, it works again.

To Reproduce
See description above and screenshot attached

Expected behavior
No exception but results returned.

Stack trace
Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer: Warning: Unhandled exception rendering component: The value cannot be null or empty. (Parameter 'mediaType')

System.ArgumentException: The value cannot be null or empty. (Parameter 'mediaType')
at System.Net.Http.Headers.MediaTypeHeaderValue.CheckMediaTypeFormat(String mediaType, String parameterName)
at System.Net.Http.StringContent..ctor(String content, Encoding encoding, String mediaType)
at RestSharp.RequestContent.AddPostParameters(ParametersCollection postParameters)
at RestSharp.RequestContent.BuildContent()
at RestSharp.RestClient.ExecuteInternal(RestRequest request, CancellationToken cancellationToken)
at RestSharp.RestClient.ExecuteAsync(RestRequest request, CancellationToken cancellationToken)
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON(Boolean forceDownload) in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 297
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON() in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 198
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at MudBlazor.MudBaseButton.OnClickHandler(MouseEventArgs ev)
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
Unhandled exception in circuit '3hFrvBILVAv_71c7LL_TtxPkV0PGJNviJWzjwzYOQgQ'.
System.ArgumentException: The value cannot be null or empty. (Parameter 'mediaType')
at System.Net.Http.Headers.MediaTypeHeaderValue.CheckMediaTypeFormat(String mediaType, String parameterName)
at System.Net.Http.StringContent..ctor(String content, Encoding encoding, String mediaType)
at RestSharp.RequestContent.AddPostParameters(ParametersCollection postParameters)
at RestSharp.RequestContent.BuildContent()
at RestSharp.RestClient.ExecuteInternal(RestRequest request, CancellationToken cancellationToken)
at RestSharp.RestClient.ExecuteAsync(RestRequest request, CancellationToken cancellationToken)
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON(Boolean forceDownload) in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 297
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON() in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 198
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at MudBlazor.MudBaseButton.OnClickHandler(MouseEventArgs ev)
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost: Error: Unhandled exception in circuit '3hFrvBILVAv_71c7LL_TtxPkV0PGJNviJWzjwzYOQgQ'.

System.ArgumentException: The value cannot be null or empty. (Parameter 'mediaType')
at System.Net.Http.Headers.MediaTypeHeaderValue.CheckMediaTypeFormat(String mediaType, String parameterName)
at System.Net.Http.StringContent..ctor(String content, Encoding encoding, String mediaType)
at RestSharp.RequestContent.AddPostParameters(ParametersCollection postParameters)
at RestSharp.RequestContent.BuildContent()
at RestSharp.RestClient.ExecuteInternal(RestRequest request, CancellationToken cancellationToken)
at RestSharp.RestClient.ExecuteAsync(RestRequest request, CancellationToken cancellationToken)
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON(Boolean forceDownload) in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 297
at DPAForPRODUCTNAMEREMOVEDBlazor.Controllers.PRODUCTNAMEREMOVED.DownloadPRODUCTNAMEREMOVEDJSON() in /Users/christian/projects/Insights-and-Services-for-PRODUCTNAMEREMOVED/DPAForPRODUCTNAMEREMOVEDBlazor/Controllers/PRODUCTNAMEREMOVED.cs:line 198
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at MudBlazor.MudBaseButton.OnClickHandler(MouseEventArgs ev)
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

Desktop (please complete the following information):

• OS: macOS Ventura 13.0.1
• .NET version .NET 7.0.100
• Version 108.0.2

Additional context
none

[alexeyzimarev]

Sorry but the issue doesn't tell enough to diagnose the problem or even understand what the problem is. Please provide more details following the issue template.

[cheindel]

@alexeyzimarev Sorry, I was in a rush. I hope it is more clear now.

[jhudsonWA]

I get the same thing with the same version and .NET 7 using the AddFile method

request.AddFile("attachment", attachment.FileBytes, attachment.FileName);

Also tried passing a content type and same error when var response = client.ExecuteAsync(request); is called.

The value cannot be null or empty. (Parameter 'mediaType')

Happy to complete another issue, but the subject is the exactly the same, even if the method to get there is slightly different.

[nesc58]

When changing the TargetFrameworks of RestSharp to net7.0 the error occurs in MultipartFormDataTests as well.

I have looked at the microsoft implementation and there are some changes.

.net6.0 implements a check to use the DefaultMediaType fallback when the given mediaType is null.

public StringContent(string content, Encoding? encoding, string? mediaType) : base(GetContentByteArray(content, encoding))
{
    // Initialize the 'Content-Type' header with information provided by parameters.
    MediaTypeHeaderValue headerValue = new MediaTypeHeaderValue((mediaType == null) ? DefaultMediaType : mediaType);
    headerValue.CharSet = (encoding == null) ? HttpContent.DefaultStringEncoding.WebName : encoding.WebName;
    Headers.ContentType = headerValue;
}

.net7.0 deimplements the check and changed the method signature (questionmark is removed)

public StringContent(string content, Encoding? encoding, string mediaType) : this(content, encoding, new MediaTypeHeaderValue(mediaType, (encoding ?? DefaultStringEncoding).WebName))
{
}

[alexeyzimarev]

.NET seven will be added as a direct target for v109 and will be executing tests for the target SDKs in the pipeline. We'll see what fails and what requires fixing.

Thanks for reporting. I haven't seen this particular one in the list of breaking changes. I guess, in time we might get more of those, unfortunately.

[alexeyzimarev]

Ok, basically the fix is to provide the default value for the Parameter.ContentType property.

[alexeyzimarev]

The workaround for the current RS version would be to add the text/plain content type to POST parameters. It's an optional argument.

[jhudsonWA]

The workaround for the current RS version would be to add the text/plain content type to POST parameters. It's an optional argument.

Testing now, i’ll report back.

[jhudsonWA]

This still fails with the mediaType error. I also tried to pass in the actual type "application/pdf" and same error. Again my issue is a different path to get the same error.

[alexeyzimarev]

I haven't seen failed tests with files. I only reproduced the multipart form issue, and the workaround applies there.

I will double check the tests for AddFile but I haven't seen anything breaking there.

[jhudsonWA]

I’ll create a test project if I have to. This call with or without the type results in the same error me i fortunatly. :(