[German]Microsoft has already published a support article on June 19, 2023, which deals with a problem under Microsoft 365 in connection with Outlook. Outlook starts extremely slowly in certain situations and gets stuck in the startup logo. The cause is probably an unexpected switch from REST to MAPI.
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Outlook hangs at startup
Microsoft has published this support article dated June 19, 2023, Microsoft states that there are problems with Outlook. It states:
Sometimes Outlook seems to synchronize the entire OST file on all or most startup operations. Outlook gets stuck at the startup screen for a long time before finally opening and working normally.
Examining the profile and OST file names, it appears that no new OST files are being created (this would also appear in the application event logs if this were the cause).
Affected people often report that Outlook opens without delay when they cancel the opening and try again. They also note that Outlook sometimes refuses to start at all when they have switched to airplane mode, causing this error:
"Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed."
Microsoft says that a known cause for this symptom is a re-priming of the cache. When priming, the cache is filled with data again. Microsoft says this is to be expected if the user has created a new profile or manually switched from REST to MAPI. This happens if he has disabled "shared calendar enhancements."
Microsoft says that due to endemic issues with reading the status of enabled features in MAPI-based non-Office applications, however, running such applications can unexpectedly force this switch.
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Microsoft's Workaround
Within the support article Microsoft says, that the Outlook team is looking for a solution to the problem, but it is not yet available. The whole thing only occurs because Outlook has problems determining the "default" status of the cache. The reason: Outlook and non-Office MAPI applications like MFCMAPI get different results.
A workaround is to use the Group Policy setting from the article How to enable and disable the Outlook calendar sharing updates. To do this, open the registry editor regedit.com and then navigate to the following key:
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Options\CalendarThere, the 32-bit DWORD value RestUpdatesForCalendar has to be set to 1 to force the use of the REST API. Alternatively, the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\Calendarand enter the above DWORD value there. In the support article, Microsoft also gives the option to force the use of REST in the Outlook settings (but this enables the "Shared Calendar Improvments" in Outlook). Final question: Is anyone from the readership affected by this bug at all?
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