[German]If you are experiencing an error message "xxxx cannot open or save any other documents ..:" when opening an Office document with Office apps from the Store on Windows 10 2004 or 20H2, this is a bug caused by a February 2021 preview update. Microsoft has documented the issue and also fixed it.
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Memory error in Office prevents open documents
Users who wanted to open documents in Microsoft Word, Microsoft Excel or other Office applications might experience the following error message suddenly appearing on Windows 10 2004 or 20H2:
Microsoft Excel cannot open or save any more documents because there is not enough memory or disk space available.
The name Excel can be replaced by other Office applications such as Word. The application in question then went into an error state, refusing to open any more documents – even though there was enough RAM or hard disk space available.
Root cause Update KB460138 from February 2021
Microsoft has probably analyzed the problem and documented it accordingly in the Windows 10 status area as of March 13, 2021. The error only occurs when:
- Microsoft Office apps from the Microsoft Store were installed on the machine and an attempt was made to open a document in such an app, which then triggered the use of the Protected View (read only) feature.
- the machine is running Windows 10 2004 and 20H2 and the cumulative update KB4601382 dated February 24, 2021 was installed (a preview update, which is actually optional).
The protected view is a new security feature. It is intended to prevent malware from spreading under Windows when Office documents are opened. In managed systems, where preview updates are not necessarily installed, the bug did not appear. The same probably applies to Office installations that were performed locally (not via the Store) (my interpretation: the function in question was not implemented there).
Bug fixed by Microsoft via KIR
The approach Microsoft used to fix the problem is interesting. It can use the Known Issue Rollback (KIR) feature. I had heard of this feature before, but had not looked into it. Microsoft introduced this new feature on March 2, 2021 in the Techcommunity post Known Issue Rollback: Helping you keep Windows devices protected and productive. In short, Known Issue Rollback (KIR) is a new feature that allows an affected device to quickly return to productive use if a problem occurs during a Windows update.
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Microsoft probably introduced the whole thing starting with Windows 10 version 2004 to roll back issues that occur due to non-security updates. If monthly updates are released that contain quality changes, Microsoft also makes these patches eligible for the Known Issue Rollback (KIR) feature.
Some versions of Windows 10 prior to version 2004, such as versions 1909 and 1809, have partial Known Issue Rollback (KIR) support built into the operating system. Microsoft says it uses this support whenever possible when providing updates for these versions.
If Microsoft determines that incorrect or unintended behavior is triggered by one of these updates, that behavior can be rolled back remotely using the new KIR feature. This is controlled by Microsoft, but only if a critical bug (called a critical regression) is detected. Details on the feature can be found in the Techcommunity post Known Issue Rollback: Helping you keep Windows devices protected and productive. (via)
On the one hand, I find this approach extremely exciting because it allows Microsoft to remotely roll back a critical bug in an automated way. But there is also a second side, where I am rather wait-and-see. It is again a point where the administrator is taken out of control. If updates are installed automatically, without any possibility for the administrator to intervene, the administrator is dependent on Microsoft reacting and KIR working. And there is the latent danger that even less testing is done (let's just take the update back if there are problems).
