KoekieMie

Still having the same issue for quite a while when checking the MDB_ONLINE and MAPI_NO_CACHE flag (eg. for https://learn.microsoft.com/en-us/outlook/troubleshoot/calendaring/errors-when-configure-free-busy-or-delegate-information#method-2-use-mfcmapi-tool) All the proposed solutions are already done, nothing works (Open Outlook...

Just discovered that in my case the error was caused by an outbound Firewall Rule blocking MFCMAPI...