Microsoft fixed a Y2K-style bug that broke Exchange email

Microsoft kicks off 2022 with a flashback to Y2K bugs. Bleeping Computer reports that the company has released a workaround for a bug that disrupted email delivery for on-premises Exchange 2016 and 2019 servers on New Year’s Day. As users found out, Exchange tried to store version date checks for its antivirus scanning engine in a 32-bit integer variable – a big problem when a date from January 1, 2022 was too large. On new checks, the malware engine crashed and email was left in a queue.

The workaround uses a PowerShell script to pause two services, replace the older antivirus engine files with newer ones that use a new number sequence, and restart operations. The solution requires manual input and may take a long time to deploy for larger companies, but an automated solution is in development.

This should not affect other Exchange customers. The timing is also “ideal,” as a holiday weekend likely limited email demand. However, company IT executives probably didn’t want to start patching servers in 2022, and it’s unclear why Microsoft didn’t foresee a date issue with software released just a few years ago. Whatever the reasoning, this serves as a clear lesson on anticipating date bugs.

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