The messaging Interfaces have returned an unknown error.

%3CLINGO-SUB%20id%3D%22lingo-sub-3373551%22%20slang%3D%22en-US%22%3EThe%20messaging%20Interfaces%20have%20returned%20an%20unknown%20error.%3C%2FLINGO-SUB%3E%3CLINGO-BODY%20id%3D%22lingo-body-3373551%22%20slang%3D%22en-US%22%3E%3CP%3EKeep%20getting%20the%20same%20error%20for%20different%20shared%20mailbox%20for%20multiple%20users%26nbsp%3B%3C%2FP%3E%3CP%3EEnvironment%20-%20Exchnage%20Hybrid%26nbsp%3B%3C%2FP%3E%3CP%3Eusers%20are%20migrated%20to%20cloud%20-%20all%20cloud%20now%20(remote%20mailboxes%20on%20premise)%3C%2FP%3E%3CP%3Eshared%20mailboxes%2Fcalendars%20-%20hybrid%26nbsp%3B%20(rmeoe%20mailboxes%20on-premises)%26nbsp%3B%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3EIssue%20is%20not%20happening%20in%20OWA%2C%20only%20Outlook%20Desktop%26nbsp%3B%3C%2FP%3E%3CP%3EOffice%20suite%20is%20updated%20to%20latest%20version%26nbsp%3B%3C%2FP%3E%3CP%3EProfiel%20reconfigure%20has%20been%20done%20-%20not%20helped%3C%2FP%3E%3CP%3Epermissions%20rmeoved%20for%20delegates%20and%20calendar%20%2C%20but%20issue%20still%20persists%3C%2FP%3E%3CP%3EError%20happens%20only%20when%20modifying%20an%20existing%20event%20in%20Calendar%20of%20a%20Shared%20Mailbox%20by%20a%20delegate%26nbsp%3B%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3ENeed%20suggestions%20from%20whoever%20has%20seen%20this%20before%20and%20from%20Outlook%20MVP's%20%2F%20Product%20Group%20Team.%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3E%3CSPAN%20class%3D%22lia-inline-image-display-wrapper%20lia-image-align-inline%22%20image-alt%3D%22gcostallsolidtechca_0-1652480324827.png%22%20style%3D%22width%3A%20400px%3B%22%3E%3CIMG%20src%3D%22https%3A%2F%2Ftechcommunity.microsoft.com%2Ft5%2Fimage%2Fserverpage%2Fimage-id%2F371588i23851FDC63B128FD%2Fimage-size%2Fmedium%3Fv%3Dv2%26amp%3Bpx%3D400%22%20role%3D%22button%22%20title%3D%22gcostallsolidtechca_0-1652480324827.png%22%20alt%3D%22gcostallsolidtechca_0-1652480324827.png%22%20%2F%3E%3C%2FSPAN%3E%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3CP%3E%26nbsp%3B%3C%2FP%3E%3C%2FLINGO-BODY%3E
New Contributor

Keep getting the same error for different shared mailbox for multiple users 

Environment - Exchnage Hybrid 

users are migrated to cloud - all cloud now (remote mailboxes on premise)

shared mailboxes/calendars - hybrid  (rmeoe mailboxes on-premises) 

 

Issue is not happening in OWA, only Outlook Desktop 

Office suite is updated to latest version 

Profiel reconfigure has been done - not helped

permissions rmeoved for delegates and calendar , but issue still persists

Error happens only when modifying an existing event in Calendar of a Shared Mailbox by a delegate 

 

Need suggestions from whoever has seen this before and from Outlook MVP's / Product Group Team.

 

gcostallsolidtechca_0-1652480324827.png

 

 

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