Title: WorkingMessageHandler error
Last modified: October 6, 2024

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# WorkingMessageHandler error

 *  Resolved [NrFive](https://wordpress.org/support/users/nrfive/)
 * (@nrfive)
 * [1 year, 8 months ago](https://wordpress.org/support/topic/workingmessagehandler-error/)
 * Hi!
 * Recently updated the entire site (www.jakoeb.com) and just noticed that every
   page where I have a PDF embedded, it now says:
 * **Setting up fake worker failed: “Cannot read properties of undefined (reading‘
   WorkerMessageHandler’)”.**
 * I’m assuming there might be a mismatch with version, since on the plugin site
   it mentions that the plugin hasn’t been updated to work with the latest WordPress
   version, but just wanted to double check with you guys.
 * Disabling the PDF Embedder plugin removes the error, but of course it also won’t
   display any PDFs.
    -  This topic was modified 1 year, 8 months ago by [NrFive](https://wordpress.org/support/users/nrfive/).
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fworkingmessagehandler-error%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Author [Slava Abakumov](https://wordpress.org/support/users/slaffik/)
 * (@slaffik)
 * [1 year, 8 months ago](https://wordpress.org/support/topic/workingmessagehandler-error/#post-18058900)
 * Hello there,
 * Most likely it happens due to some caching plugins.
 * We have a doc article on this topic: [https://wp-pdf.com/kb/setting-up-fake-worker-failed-error-message/](https://wp-pdf.com/kb/setting-up-fake-worker-failed-error-message/)
 * Please read and let us know whether it helped.
 *  Thread Starter [NrFive](https://wordpress.org/support/users/nrfive/)
 * (@nrfive)
 * [1 year, 8 months ago](https://wordpress.org/support/topic/workingmessagehandler-error/#post-18058983)
 * Fixed thank you so much!
 * For others if they ever stumble upon it. Latest version of Jetpack now supports
   caching and has **“aggregate JS”** under the tab **“Boost”**, which I haven’t
   see before. Disabling that option makes the PDF Embedder work right away.

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘WorkingMessageHandler error’ is closed to new replies.

 * ![](https://ps.w.org/pdf-embedder/assets/icon.svg?rev=3227003)
 * [PDF Embedder](https://wordpress.org/plugins/pdf-embedder/)
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 * 2 replies
 * 2 participants
 * Last reply from: [NrFive](https://wordpress.org/support/users/nrfive/)
 * Last activity: [1 year, 8 months ago](https://wordpress.org/support/topic/workingmessagehandler-error/#post-18058983)
 * Status: resolved