Import: Users Excel Import may cause a silent error if the file format is incorrect

Issue Summary

When importing users using an excel .xml or .xls file, a 500 error may occur without notifying the user of the problem.
The user only sees a blank/empty area (with a "spinning wheel") instead of the preview of the users’ data contained in the file.
There is no notification that the system encounters a 500 error unless the user goes to the 'Network' tab or the console of the web browser developer tools.

Steps to Reproduce

It may be necessary to engage with the customer to do the import, as it's not possible to replicate on a test instance.

1. Go to the 'People' page
2. Click on More Actions
3. Click on Import User Record
4. Browse and choose the .xml or .xls file you want to import
5. Click on Import Items

Expected Results

Visual information is provided to the user (in a form of a popup with a message) if the file format or the file is not correct.

Actual Results

User experiences a blank/empty Data Preview page with or without a "spinning wheel".
A 'silent' 500 Internal Server Error is thrown in the background which can be seen by going to the 'Network' tab or the console of the web browser developer tools:

and

Looking at the Spunk log we can see the error such as like:

{ [-]
   ASP_function: Error.asp
   ErrorId: 2465
   PageName: People
   correlationid: TNsyiDBxfN5KBinpoUEt65FqN7x94lW0xCkDYbIkZbk=
   customer_db: Alignsupport
   error_aspcode:
   error_aspdescription:
   error_category: Microsoft VBScript runtime 
   error_column: -1
   error_description: Object required: 'UsersHeaderRow(...)'
   error_file: /AjaxFiles/AjaxUserImport.asp
   error_line: 84
   error_number: -2146827864
   error_source:
   log_type: exception
   logfrom_location: Website-ASP
   timestamp: 2022-11-18T05:47:13.404000-05:00
   url: https://alignsupport.jiraalign.com:443/AjaxFiles/AjaxUserImport.asp?Type=1&FileName=Export_User_Attributes_Report_KO500Error%281%29.xml
   urlverb: POST
   user: 661802
   version: 10.113.2.25772
}

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available
When you edit the excel file make sure to not alter the first 4 rows of the template and to always save the file as Excel 2004 XML spreadsheet file format.