[Qtwebengine] Uncaught TypeError: channel.execCallbacks[message.id] is not a function

[Goldberg, Ilya (DWFN)]

Hi All,
We are migrating from Qt5.5 to Qt5.12.8 on CentOS 7, 64bit x86 processor.

Qt main application is working. Our webpage is based on JavaScript, running on Apache-Tomcat. It is using channel back to the main application (using qtwebchannel.js) as we need to know when user wants to return from the webpage into our main app.
The webpage works fine under Qt5.5.
After upgrading to Qt5.12.8 found that the webpage is broken (all elements are in wrong places and it does not work as expected).
In the log file found multiple messages: "Uncaught TypeError: channel.execCallbacks[message.id] is not a function".

Did anyone experienced similar error messages?
Any clue on fixing it?

Thank you.
PROPRIETARY: This e-mail contains proprietary information some or all of which may be legally privileged. It is intended for the recipient only. If an addressing or transmission error has misdirected this e-mail, please notify the author by replying to this e-mail. If you are not the intended recipient you must not use, disclose, distribute, copy, print, or rely on this e-mail.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/qtwebengine/attachments/20200422/5c57082b/attachment.html>