NM: Windows UI error Common Migration Tool has stopped working (4311916)

Issue
When migrations are processed on a worker a Windows UI dialog can be displayed if there is an error in the worker processing.

"A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available"

This can be a result of missing or incorrect requirements software or an issue with bad data on a specific source Notes message.
If this occurs a Windows UI error will be presented stating that the Common Migration Tool has stopped working and will ask to check online or close the program.
This can have additional details indicating that the Application Name: CMTProxy.exe is the item that failed.
The Windows UI dialog will prevent the migration worker from completing the controller update for the account and the re-queue of the account until the dialog is actioned by selecting Close the program.

Solution

Review the below two solutions depending on when the migration worker displays the Windows UI dialog.
Note: the dialog can be closed by selecting "Close the program"

Migration fails immediately:
If a migration account does not connect to the target mailbox (or PST) and no migration log is created then review the below linked article.
NM: Migration fails immediately

Migration fails during processing:
If a migration does connect to the target system but fails during the migration of the source Notes data then this would likely be due to bad source data that is causing a Notes or Outlook fault.
In this case closing the Windows UI dialog will exit the current migration job and re-queue the account. The re-queue will process the migration automatically and will skip bad source document (as well as any previously migrated data).
The migration log can be reviewed for the source data item that caused the processing fault. The log will be on the migration worker (C:\Program Files(x86)\Binary Tree\CMT for Exchange\Worker\Logs) and also copied to the migration controller (C:\Program Files\Binary Tree\CMT for Exchange\Logs).
Note: the migration re-queue process does have a limit to the number of attempts (10) after which the account will not be automatically retried but can be set to migrate again if necessary if it shows as failed.

Additional Optional Update
The Windows UI dialog can be suppressed on a migration worker which will remove the requirement for a manual update to close the dialog on the worker and have the re-queue process update automatically.
This requires a Windows Registry update on the worker with the below Reg_DWord key being set (or created).
Note: modifying the Windows Registry can have unexpected results and should be verified with Microsoft Support if there are any queries.

HKEY_CURRENT_USER\Software\Microsoft\Windows\Windows Error Reporting
Key: DontShowUI
Value: 1

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