Getting DataCloneError: Failed to execute 'postMessage' on 'Worker': ArrayBuffer at index 0 is already detached, when trying to open signed PDF in WebViewer

zaid.jeelani · February 13, 2026, 7:08am

WebViewer Version: 11.3.0

We are experiencing an issue with opening a signed PDF in one of our environments.

We currently have two separate environments running the same version of WebViewer. In Environment A, the signed PDF opens without any issues. However, in Environment B, attempting to open the same signed PDF results in the following error:

DataCloneError: Failed to execute ‘postMessage’ on ‘Worker’: ArrayBuffer at index 0 is already detached.

What could cause this issue and what steps would you recommend to diagnose and resolve this issue?

system · February 13, 2026, 7:09am

Hello, I’m AiRon, an automated tech support bot
While you wait for one of our customer support representatives, I can help you with your question.

It sounds like you’re encountering a DataCloneError related to an ArrayBuffer being detached when trying to open a signed PDF in WebViewer. This error typically occurs when the buffer that is being sent to a web worker has already been used or manipulated in a way that detaches it before the transfer is complete. The issue may be environmental or related to how resources are handled between your environments.

Some things you can try:

Ensure that the PDF file is not being manipulated or accessed by other processes before being passed to the WebViewer, as this can cause the ArrayBuffer to be detached.

Check the network and file handling configurations in Environment B to ensure that they match Environment A, particularly regarding file streaming and handling.

Verify that the WebViewer initialization and loading code is consistent across both environments. Any differences could lead to this issue.

Update the way you pass data to the WebViewer, using blob URLs or other methods that do not involve direct ArrayBuffer manipulation.

Consider upgrading to a newer version of WebViewer if feasible, as there may be bug fixes related to this issue.

Here are some resources that might help you:

WebViewer Server Configuration Guide: Ensure your server configuration is optimal for handling PDF files.

Digital Signatures Guide: Understand how digital signatures are managed and any potential impacts on file handling.

WebViewer Server Performance: Tips for optimizing server performance that might affect file handling.

Digital Signature Showcase Demo: Example implementations that might provide insight into handling signed PDFs.

Interacting with Signature Fields: Details on working with signature fields programmatically.

Hopefully, this helps you solve your problem while you wait for a human to get back to you.

jromanocarlsen · February 13, 2026, 5:57pm

Hello @zaid.jeelani,

Thank you for posting on our forum. To help us diagnose the issue further, please confirm the following:

1. Source input PDF used for testing

2. Does the failing environment have any extensions running? Are they able to reproduce the issue after clearing the browser cache and/or opening the environment in an incognito window?

3. Network panel showing all failed network traffic (ideally a .har file)

4. Can you reproduce the issue using our samples (especially on our site)? https://showcase.apryse.com/

5. Does the issue only occur in certain browsers and/or devices? If so what are the details? What are the differences between the two environments tested?

6. Are you able to reproduce this issue on our latest release (Version 11.10)?

Best Regards,
Jacob Romano Carlsen
Web Development Support Engineer
Apryse Software Inc.