[German]The June 2025 security updates for Microsoft Office cause Microsoft Outlook Classic to crash in some versions. At the weekend, Microsoft confirmed these Outlook crashes and published a workaround. I'll put this information in a separate article.
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Outlook crashes due to Office update June 2025
On June 10, 2025, various security updates were released for the Office versions currently under support (see Patchday: Microsoft Office Updates (June 10, 2025)). The updates close the remote code execution vulnerabilities CVE-2025-47162, CVE-2025-47164, CVE-2025-47167 and CVE-2025-47953, which are classified as critical with a CVEv3 score of 8.4 (see also Microsoft Security Update Summary (June 10, 2025)). With the exception of CVE-2025-47953, a display in the preview window is sufficient as an attack vector to exploit these vulnerabilities.
However, these security updates have led to users complaining about Outlook Classic crashing. After the June 2025 patchday, various readers have contacted the blog complaining about these crashes. These range from Outlook Classic crashing in Microsoft Office 2021 LTSC when handling emails (see this German comment). Double-clicking on an email or creating a new email is enough to cause Outlook to crash immediately.
According to this German comment, Outlook 2016 is also affected by the crashes. For MSI installations, the security update KB5002683 (for Outlook 2016, which closes the RCE vulnerability CVE-2025-47171) was identified as the cause. I had collected the corresponding error reports from blog readers in the blog post Office-Updates June 2025: Outlook crashes, documents can't be opened.
German blog reader MBDTeam then informed me by email (thanks for that) that not only the Office MSI versions (Office 2016) but also all C2R versions are affected (everything from Office 2016 and Office 365 that is installed via Click-to-Run). The user's Office 365 version 2408, build 17928.20572, from the semi-annual channel is affected..
Microsoft confirms Outlook crashes
Microsoft has published two support articles on the Outlook Classic crashes, which in my opinion deal with different crash problems.
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- Outlook LTSC 2019 is crashing, but this cannot be related to the June 2025 patchday. This is because Microsoft published the Microsoft support article OOutlook LTSC 2019 crashes opening Viva Engage, Yammer, Power Automate, and other emails before the patchday on June 9, 2025. Microsoft claims to have fixed the problem by June 13, 2025, but this is denied by German reader MBDTeam.
- On June 13, 2025, Microsoft published the support article Classic Outlook crashes opening or starting a new email regarding the Outlook email crash bug (thanks to German reader MDBTeam for pointing this out). There, the bug outlined above is confirmed for the monthly Enterprise Channel from version 2504 (build 18730.20122).
The latter support article on the Classic Outlook crashes in the Enterprise Channel from version 2504 (build 18730.20122) states that the problem has been escalated and is being investigated.
Microsoft provides a workaround
In the support article Classic Outlook crashes opening or starting a new email, Microsoft states that the crashes occur because Outlook cannot open the Forms Library. An expected folder under AppData in the user profile appears to be missing. According to Microsoft, virtual desktop infrastructures (VDI) are affected by this scenario. As a workaround, Microsoft therefore suggests that those affected should create the following empty folder:
C:\Users\<username>\AppData\Local\Microsoft\FORMS2
(or %localappdata%\Microsoft\FORMS2) in the user's profile folder. This should fix the crashes. I have received different feedback from those affected (one voice says that the created folder does not prevent the crashes). The tenor of most of those affected, on the other hand, was that creating the missing folder solved the crash problem. Ralf Scholten wrote in this German comment (translated below):
By creating the folder:
%localappdata%\Microsoft\FORMS2
via GPO in the user context, Outlook (LTSC 2021 / 2024, x86 and x64) can be started again without errors.
The necessary steps should be described in this article. Other readers confirm that this approach works. However, the reader notes that mails with integrated photos cannot be forwarded (when forwarding, the photos are replaced by "The linked image cannot be displayed…").
Similar articles:
Microsoft Security Update Summary (June 10, 2025)
Patchday: Windows 10/11 Updates (June 10, 2025)
Patchday: Windows Server-Updates (June 10, 2025)
Patchday: Microsoft Office Updates (June 10, 2025)
Windows 11 24H2: Out-of-Band Update KB5063060
Windows 10/11: Preview Updates May 27, 28,2025
Attention: June 2025 Patchday closes vulnerability CVE-2025-33073 in Windows
Windows network vulnerability CVE-2025-33073 (Reflective Kerberos Relay Attack)
Caution: Windows June 2025 updates bricks Fujitsu computers
Windows 10: June 2025 update KB5060533 causes Surface Hub v1 boot error
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Hello,
FYI, the problem can be also solve by starting Outlook in safe mode, outlook.exe /safe.
After doing that you should not have the problem anymore.
This should be done on each computer where Outlook crashes.
That command outlook.exe /safe creates the missing folder (afaik, MS has added this behavior).
I found out that only creating the Folder %localappdata%\Microsoft\FORMS2 did not sorted the issue…
…I also need to delete the below registry key that will be cleanly recreated from Outlook after next startup.
This Key is for Outlook 2016 and can be different for other versions:
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Forms
Cheers,
Sascha
Hi
You had to remove the registry key even with the updated Office version that's supposed to fix this issue?
Thank you