Microsoft Exchange administrators welcomed the New Year with an email blocking bug in their systems, after a coding error prevented time and date information for 2022 from being stored correctly.
The issue is affecting on-premises Exchange installations, with users reporting that versions 2016 and 2019 of Microsoft's communications and calendaring server aren't able to send or receive email.
A coding mistake after a January 1 auto-update is causiing the FIP-FS anti-malware service to crash with the 0x80004005 error code when it encounters 2022 dates.
Date values such as 2201010001 cannot be converted to long 32-bit integers, as they exceed the maximum of 2^31 or 2147483647 that can be stored.
Converting a formatted date into an i32 is a galaxy brain move I never would've thought of. I'm sure that the source code has a comment somewhere saying "fixme: should be changed at some point"— ｡ﾟ･\m\(＞Д＜＃)/m/･ﾟ｡️ (@dada78641) January 1, 2022
Microsoft has acknowledged the bug and is working on an update.
"Our engineers were working around the clock on a fix that would eliminate the need for customer action, but we determined that any change that did not involve customer action would require several days to develop and deploy," the company said.
"We are working on another update which is in final test validation.
"The update requires customer action, but it will provide the quickest time to resolution."
Users affected by the bug can use the Disable-AntiMalwareScanning.ps1 PowerShell script to disable the malware scanning.
A restart of Exchange Server is required for the workaround to take effect.