A Microsoft Office update has pranged customised copies of Word.

The upgrade for Word version 16.0.6366 renames users' Normal.dotm file. This means a new and empty Normal.dotm is created when Word is restarted after the update is applied, giving people the impression their customizations have been lost. Complaints are landing on the Microsoft Office forum page, here.

The glitch was initially blamed on a Windows 10 security update, but the bug was eventually tracked down to a dodgy Office patch.

The flaw is a pain in the ASCII for anybody who customised their copy of Word with macros, auto-corrections, and autotext for their own particular needs. Normal.dot – or, rather, Normal.dotm these days – is the database that stores such settings. If Word can’t find this file, it recreates it from vanilla factory settings.

Doug Robbins, a Word MVP, wrote on the Microsoft community forum: “In 30+ years of using Word, including 2016 on Windows 10, I have never had a Normal.dot or more recently Normal.dotm template simply disappear.”

A Microsoft group engineering manager for Word posted to the forum that Microsoft is looking into the problem. (To restore the renamed Normal.dotm, check out this suggested solution.)

“This was not an intentional change and we (the Word product team) are working to understand both the cause as well as what steps customers can take to either avoid or recover from this,” the Microsoftie said. ®