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RTE Insert Assets Inconsistencies

We are using the Rich Text Editor to build content and we allow audios, images, and videos. We have an API we call to upload the assets to so we can save them to AWS S3 and return the full URL. We are using OnImageUploadSuccess for images and FileUploadSuccess for audios & videos. When we select an asset via "Insert Audio", "Insert Image", and "Insert Video", the API is properly called, the events fire to get the file path and the asset is properly added to the editor. When we drag-and-drop or copy/paste, it does not work for audios and videos, but seems to work for images.

Please see this video where we try all 3 methods (drag-and-drop, copy/paste, and "Insert" button) for all asset types (audio, image, video):
https://www.loom.com/share/dbcd642081324e0cbee86a3107122a74

We have tried various settings and audio & video always render the file as a blob.

Attached is a sample application. Be sure to set the key in Program.cs.

Note: When the API is called, it returns a hard-coded path so you have a real, working URL. Our code actually does a lot more, but that's irrelevant.


Attachment: SFIssues20260225_3a173802.zip

14 Replies 1 reply marked as answer
BP Brian Pautsch February 25, 2026 07:35 PM UTC

UPDATE: I just realized the code I uploaded isn't using the latest nuget packages. Please update them first. The results are better, but there are still issues. You can now drag in an mp3, but it's still rendering as a "blob".

The main issue is: Why aren't audios and videos rendering with the URL returned from the API?


KP Kokila Poovendran Syncfusion Team February 27, 2026 01:41 PM UTC

Hi Brian Pautsch


We have considered the reported issue “Audio/Video files dragged into the editor are uploaded as Blob URLs instead of API-returned URLs" as a bug from our end and the fix for the issue will be included with our upcoming patch release ,which is expected to be rolled out in mid-March 2026. Now you can track the status of the reported issue through the feedback below,


Feedback: https://www.syncfusion.com/feedback/72918/audio-video-files-dragged-into-the-editor-are-uploaded-as-blob-urls-instead-of-api


Disclaimer: “Inclusion of this solution in the weekly release may change due to other factors including but not limited to QA checks and works reprioritization.”

 


KP Kokila Poovendran Syncfusion Team March 17, 2026 07:51 AM UTC

Hi Brian Pautsch,


We have included the fix for the issue "Audio/Video files dragged into the editor are uploaded as Blob URLs instead of API-returned URLs" with our package version “32.2.9”. Therefore, we recommend upgrading to our latest version to resolve the current issue.


Release Notes: https://blazor.syncfusion.com/documentation/release-notes/32.2.9?type=all#bug-fixes-3

Root cause

  • After the file upload completes, the server triggers videoDropSuccess / audioDropSuccess.
  • These callbacks did not include the custom URL configured by the customer.
  • Because of this missing URL:
    • The editor could not retrieve the custom server‑returned URL.
    • As a fallback, it inserted a Blob URL, causing incorrect media sources.

BP Brian Pautsch replied to Kokila Poovendran March 18, 2026 02:22 PM UTC

Kokila,

It is only partially fixed. For all 3 media types (audio, image, video), we tested drag/drop, copy/paste and select/insert.

Video: https://www.loom.com/share/1644255eb69146f2a797519c20bf0d02

Results:

Audio
Drag/Drop: good
Select/Insert:  good
Copy/Paste: "src" is getting added to "audio" tag when it should be updating the "src" tag. See in video at 50 sec.
The "alt" is a bit weird too...it should probably not be added.

Image
Drag/Drop: good
Select/Insert:  good
Copy/Paste: good

Video
Drag/Drop: good
Select/Insert:  good
Copy/Paste:  "src" is getting added to "audio" tag when it should be updating the "src" tag. See in video at 2:35.
 The "alt" is a bit weird too...it should probably not be added.

Thanks,
Brian


KP Kokila Poovendran Syncfusion Team March 19, 2026 08:53 AM UTC

Hi Brian Pautsch,


Thank you for sharing the detailed video and for thoroughly retesting all scenarios. We sincerely apologize for the inconvenience caused.

We have reviewed the behavior, and we can confirm that the issue you reported—where the src attribute is added to the audio/video tags during copy‑paste operations and the alt attribute is also added—is reproducible on our side as well. We will be addressing this in our upcoming weekly release scheduled for the end of March 2026.

You can track the status of this reported issue through the following feedback link: https://www.syncfusion.com/feedback/72918/audio-video-files-dragged-into-the-editor-are-uploaded-as-blob-urls-instead-of-api


Disclaimer: “Inclusion of this solution in the weekly release may change due to other factors including but not limited to QA checks and works reprioritization.”



BP Brian Pautsch March 30, 2026 03:26 PM UTC

Kokila - Is this still planned for release today or tomorrow?


KP Kokila Poovendran Syncfusion Team April 1, 2026 04:56 AM UTC

Hi Brian Pautsch

We have included the fix for the issue "Audio/Video files dragged into the editor are uploaded as Blob URLs instead of API-returned URLs" with our package version “33.1.46”. Therefore, we recommend upgrading to our latest version to resolve the current issue.


Release Notes: https://blazor.syncfusion.com/documentation/release-notes/33.1.46?type=all#rich-text-editor

Root Cause / Analysis

  • The response header value (name) returned from the API was not handled during audio/video paste operations.
  • The pasteSuccessHandler logic was not handling media types correctly, which caused
    • An additional src attribute to be appended directly to the <audio> / <video> element instead of updating the existing one.
    • An unintended alt attribute being added for audio and video elements.
  • These combined issues resulted in malformed media elements and incorrect source resolution.

Marked as answer
BP Brian Pautsch April 1, 2026 03:15 PM UTC

We see the updates to the individual components, but the Core is still  33.1.45.

This is preventing the components from getting upgraded.


NUGET UPDATE ERROR:

Image_2550_1775056481748


CURRENTLY INSTALLED:

Notice the Core doesn't have a 33.1.46 available to upgrade to.

Image_6835_1775056366020


BP Brian Pautsch April 3, 2026 02:29 PM UTC

Please advise


BP Brian Pautsch April 3, 2026 03:33 PM UTC

ISSUES!

We see the Syncfusion.Blazor.Core nuget package is out there now.

We upgraded to v33.1.46 and it is still wrong! This is the 2nd time we're reporting the same error after you say it's fixed. This needs to be tested / quality assured much better. We're being very helpful finding bugs and giving you helpful videos showing how to replicate them. Please take the time to FULL test the updates. This issue goes back to Feb 25th.

Issue: Now when you copy an audio or video file from n your local drive, it places a blob instead of firing the FileUploadSuccess event. It workss for images, but not for audio or video.

Please expedite this fix.


GD Gokulraj Devarajan Syncfusion Team April 10, 2026 02:03 PM UTC

Hi Brian Pautsch.

We understand the concern, especially given the time and effort you have invested in reporting and validating the behavior.

 

We have revalidated the reported issue on our side using Syncfusion.Blazor.Core v33.1.46. Based on our testing, we were unable to reproduce the behavior where copy‑pasting audio or video files results in a blob URL instead of triggering the FileUploadSuccess event.

 

Scenarios Validated on Our End (v33.1.46)

 

We tested the following cases:

  • Audio files
    • Drag and drop
    • Copy and paste
  • Video files
    • Drag and drop
    • Copy and paste 


In all cases:

  • The media files were uploaded using the configured upload API.
  • The FileUploadSuccess event was triggered as expected.
  • The src attribute was updated with the API‑returned URL.
  • The previously reported issues related to blob URLs and incorrect src updates were not observed.


We have also attached a video recording from our side demonstrating the working behavior for reference.

 

Since the issue is still occurring in your environment, we kindly request the following:

 

  1. Clear the NuGet cache completely, rebuild the project, and re‑test the scenario. 
  • dotnet nuget locals all --clear
  1. Please check whether the same issue occurs in the sample available at the link below, using version 33.1.46, and let us know if the issue is reproducible there:
  1. If the issue persists after clearing the cache and testing the sample, could you please share an updated video recording from your side showing:
    • The exact steps followed
    • The copy‑paste action for audio/video files
    • Whether the FileUploadSuccess event is triggered or not

 

Once we receive the above details, we will continue the investigation immediately and work towards a definitive resolution. We truly appreciate your patience and the valuable feedback.



BP Brian Pautsch April 22, 2026 03:01 PM UTC

You are correct. It is working now. Thank you!

One issue: When a local audio or video file is copied and pasted in the editor, event "BeforeUploadImage" is fired. It should be firing event "FileUploading". 

Note: When you select or drag in an audio or video file, the correct event fires.

We added code to check the file extensions as a workaround.


VJ Vinitha Jeyakumar Syncfusion Team April 27, 2026 05:24 AM UTC

Hi Brian,



We have considered the reported issue "Incorrect Event Triggered When Pasting Audio or Video Files in RichTextEditor" as a bug from our end, and the fix for the issue will be included in our upcoming weekly patch release scheduled for the 2nd week of May 2026



Now you can track the status of the reported issue through this feedback,


VJ Vinitha Jeyakumar Syncfusion Team May 22, 2026 11:14 AM UTC

Hi ,


We have included the fix for the reported issue "Incorrect Event Triggered When Pasting Audio or Video Files in RichTextEditor " with our weekly patch release V33.2.5. Please upgrade your package to the latest version to resolve the issue from your end.



Root Cause:
The reported issue occurs because the FileUploading event was not get invoked for media uploads, including image, audio, and video files. The BeforeImageUpload event was incorrectly triggered for all media types, instead of being restricted to image uploads only.

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