custom javascript error TypeError: rObj.firstChild.onclick is not a function

On : 8.55.01 version, Updates and Fixes, PUM environment

When attempting to navigate to the Update Manager Dashboard, the following error occurs.

ERROR
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custom javascript error TypeError: rObj.firstChild.onclick is not a function

SOLUTION:
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 1. Go into the PUM environment

2. Navigate to the Action List menu icon > My Preferences

3. Select Accessibility features off

4. Retest the issue.

5. Migrate the solution as appropriate to other environments.