"No mailbox with such guid" error

[SlavaG]

Hi,

Last week we're suffering from many office 365 errors, that started to happen out of the blue.

Now, it's a new one, we're using EWS to access office 365 , using account with impersonation rights to access another mailboxes.

Since yesterday we see high rate of error "No mailbox with such guid" on the mailbox that are really exists and valid mailboxes.

Have no idea what is going on there in Office 365, but last week it's a worst ever, 3 different issue for one week, MS support team is totally non-professional and response with "it's a connectivity issue" or "it's a 3'rd party issue, we don't solve this", even, even when we send them request / response trace, clearly showing what was request and what is response, and where's the problem. And they constantly asking for the screenshot for EWS !!!

Very sad, it was stable product, but last weeks dangerous degradation, affecting many tenants, without any one from Microsoft is taking responsibility on that. 

[#2 · Accepted solution]

Hi,

I am sorry to here , that you guys are going thorough a lot

This error is commonly caused by an unlicensed mailbox account. Check that all of the migrating mailboxes are licensed in Office 365 first.

If a mailbox account has been assigned a license and the error persists, it is usually caused by a non-Null value in the "msExchMailboxGuid" attribute of the mailbox account.

Please refer the below link for more info and let me know how it goes.
https://help.bittitan.com/hc/en-us/articles/115008114287-No-mailbox-with-such-GUID-ErrorNonExistentM...

[#3]

Well,
It's not our tenant, but customer's that
saying that mailbox are licensed, and even more up to 2 days ago, those accounts were working fine. So, I assume it's something else, it's just started to return errors on those valid, licensed and previousky working mailboxes, 2 days ago. Last week, we see strange bug from office 365, so I guess it's another one in the bugs pipeline :).
Thanks

[#4]

Have you checked " non-Null value in the "msExchMailboxGuid" attribute of the mailbox account."
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Please mark as "Answer" and give a "like" if you are satisfied with the reply

[#5]

Strange, while we tried to check the flag, with the customer, seems that mailboxes that failed with that error, found that lost their licenses. They were licensed and somethow license was vanished from them.