Telerik Reporting 2025 Q1 and .NET 8: "Invalid Report Type" in Linux Docker Container

[Chris]

HI

I have written a .NET 8 MVC Application using Telerik Reporting 2025 Q1.
The report works fine when published to local IIS, but fails in a Linux Docker Container:

  http://localhost:8080/Home/Report


Error in browser console : 

Failed to load resource: the server responded with a status of 500 (Internal Server Error) /api/reports/clients/af4ec7bb24c/parameters  report:1
Uncaught (in promise) Invalid report type


HTML5 Report Viewer in View (ReportViewer.cshtml):

  $("#reportViewer1").telerik_ReportViewer({
    serviceUrl: "@Url.Content("~/api/reports/")",
    reportSource: {
        // report: "MyReport.trdp"
        report: "@Model.ReportType.AssemblyQualifiedName",
        parameters: {}
    },

    ...

  });


After trying again and again, I finally found the problem: it's the default image set in PictureBox1.

  Report1.Designer.cs

    this.pictureBox1.Value = ((object)(resources.GetObject("pictureBox1.Value")));

  Report1.resx:

  <assembly alias="System.Drawing" name="System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
  <data name="pictureBox1.Value" type="System.Drawing.Bitmap, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
  <value>
    iVBOR......ggg==
  </value>
</data>


Once I removed the PictureBox, the report viewer worked correctly in the Linux Docker container.


My Questions:

1. Why does the Report Viewer show only a weak message "Invalid report type" ?
.NET 8 no longer supports System.Drawing.Bitmap in Linux Docker Container,
A clearer error message than just 'Invalid report type' would be helpful.

2. Is there any config to enable more detailed error output?
How can PictureBox default images set in the report designer be supported in .NET 8 Linux Docker containers ?

*The /api/reports/formats endpoint works fine.


Environment:

Windows 10 Pro
Visual Studio 2022
.NET 8 (latest)

Docker Container:
Ubuntu 22.04 (VirtualBox)
Docker version 27.5.1

 

Best regards

Chris

[Dimitar]

Hello Chris,

Thank you for the provided information about your scenario!

Generally, we try to show less detailed messages to the client as this seems to be the preferred option most times based on user feedback. When debugging issues with the rendering of the report, especially when the Reporting service returns a 500 Internal Server Error response, it is recommended to investigate the server-side exceptions which can be logged with a trace listener - How to troubleshoot errors in ASP.NET Core projects - Telerik Reporting.

Regarding the question about using the PIctureBox item in type report definitions when the OS is Linux, to avoid errors on LInux/Mac, the image must be saved in the RESX file as a base64 string, please take a look at the Resolving the "You can assign System.String, IImage, System.Drawing.Image" Error in Telerik Reporting - Telerik Reporting article for more information on the topic.

I would also recommend visiting the Using Telerik Reporting with .NET 6+ or Standard - Telerik Reporting article and having a look at the Deploying on Linux section which lists all dependencies that must be installed for the engine to work properly on Linux.

I hope that the provided information will help. Please let me know if I can assist with anything else.

Regards,
Dimitar
Progress Telerik