KB45645: "JavaScript errors were encountered on this page" error appears when changing a selector in a filter panel in Interactive Mode in MicroStrategy Web 9.3.1 - 9.4.1.

SYMPTOM:
 
When the user runs a document in Interactive Mode or Editable Mode, if they click on a header in the grid,  for example to sort a column, and then interact with a selector in a filter panel, the following error appears:
 
 

*JavaScript errors were encountered on this page. *Click here for more details.

Strategy client-side error log:

TypeError: Cannot read property of 'xxx' of null

• Create a report like shown in the image below.
• Convert it into a document.
• Add a panel stack, Parent Panel Stack.
• Add a second panel stack inside the Parent Panel Stack, Child Panel Stack.
• Add the grid to the Child Panel Stack.
• Add a filter panel stack with a selector based on an attribute from the grid.
• Make sure the selector only tagets the Parent Panel Stack. The final dashboard looks as below:
  

• Run the document.
• Click on one of the grid headers.
• Now attempt to interact with the selector in the filter panel.
• Notice the javascript error.

CAUSE:
 
This is a known issue in Strategy Web 9.3.1 - 9.4.1. This issue occurs when the filter panel is created after the parent panel stack. 
 
ACTION:
 
Contact Strategy Technical Support for an update regarding this issue.
 
WORKAROUND:
 
There are two workarounds for this issue; use one or the other:

• Have the selectors in the filter panel target the child panel stack rather than the parent panel stack.
• Create the filter panel before creating the parent panel stack. This can be done by deleting the parent panel stack and then recreating it, and can be confirmed by making sure the filter panel is listed after the parent panel stack in the document structure, as shown below:
  

 
The internal Strategy reference number for this issue is 814347.