Media Upload Not Responding – /umbraco/backoffice/umbracoapi/media/PostAddFile Hangs on New Upload (Umbraco 13.9.3)

I’m working on an Umbraco 13.9.3 project, running directly from Visual Studio (IIS Express). I’ve encountered a strange issue when uploading new media files.

Problem:

When uploading a new file via the media section (drag-and-drop area or media picker via a content node), the request to:

/umbraco/backoffice/umbracoapi/media/PostAddFile

hangs and does not respond.

After a long wait, I get a rejection from AngularJS (likely a timeout or unresolved promise).

However, once the Media folder is refreshed, the uploaded file is visible — so the file does get uploaded, but the UI hangs and doesn’t respond as expected.

Additional Info:

  • I’m able to replace existing media item files using the File Upload property without any issues.

  • This behavior is only happening when adding new media, not replacing.

  • The issue occurs only on my system — my colleagues do not experience the issue using the same codebase and database.

  • I also created a new Umbraco 13.9.3 project within the same solution, and the file upload works perfectly there.

  • The current project is working with a 10 GB database and a large number of content nodes, which might be relevant to the performance or request handling.

  • No errors appear in the server logs.

  • Using Chrome Developer Tools, the POST request just stays pending with no response from the server.

  • Running the project directly from Visual Studio (IIS Express).

Has anyone encountered something similar or have any suggestions? I’m open to configuration tweaks or debugging tips. Any help would be greatly appreciated.

Hi @sumeshkp18,

There is a chance that you are encountering an issue related to file uploading limitations.

I see that you are able to replace existing file, but I’m not sure if you are trying to replace existing file with a file for which the uploading is not forking or other file.

Please keep in mind that during replacing a file a different endpoint is being used.

We know that editors are struggling during uploading new files in Umbraco. Therefore, we have decided to publish a new article which is about common issues with uploading large files. I guess that you will be able to find a solution there.

Moreover, please keep in mind that a new Umbraco v13.12.0 is just around the corner in which the issue with the MaxRequestLength option is resolved.

Best!

WT

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