What is KB890830? It has been hanging since 2010 and now it is hanging on my Windows10 x64 PC in late 2021

Windows Malicious Software Removal Tool x64 - v5.95 (KB890830) Status: Installing - 0%

Been that way now for a good 45 minutes.

What causes the hang? I see postings from 2010 where the same issue is reported. Are the KB numbers recycled?

P.S. Troubleshooter couldn't identify the problem.

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