Exchange Mailbox Migration errors

I am migration 44 mailboxes to Office365. I'm using a tool called migration-wiz.

So I had to give my admin account and give myself full permissions so this tool can gain access to the mailboxes and migrate the data.

After adding myself with those full access permissions to some users everything was good. But after a while I started to get a warning upon completion which i attached the photo below.

Now I checked my event log and I see this error

"Process w3wp.exe () (PID=4260). User 'Sid~ABC\john~EWS~false' has gone over budget '326' times for component 'EWS' within a one minute period. Info: 'Policy:DefaultThrottlingPolicy_8bbb676e-a705-4b0f-a58b-30777c69d87b, Parts:CAS:325;'. Threshold value: '100'."
Who is Participating?
Adam BrownConnect With a Mentor Sr Solutions ArchitectCommented:
Yeah. There's a feature you can enable called impersonation. What's happening is you are exceeding the Office 365 throttling policy limit for number of connections to the service. Impersonation will allow you to impersonate the mailbox you're migrating to and deal with the throttling limits of each user's mailbox instead of just yours. Connect to the Office 365 Exchange remote powershell and run this:

new-managementroleassignment -role "applicationimpersonation" -user

That will set up your admin account in O365 to run in impersonation mode, which should fix that error for you.
IT_FanaticAuthor Commented:
im on my computer. Where is the power shell for office 365?

The script would be this?

new-managementroleassignment -role "applicationimpersonation" -user
Jeffrey Kane - TechSoEasyConnect With a Mentor Principal ConsultantCommented:
An overview of why this is happening is here:
and a bit more on the MigrationWiz blog here:

You cannot change the Throttling Policy on Office 365, as acbrown2010 described above.

Unfortunately, you must just tough it out and wait for the batches to go through -- which they eventually will.  

Try migrating mailboxes in smaller batches -- or migrate very large mailboxes (over 20GB) by themselves as a single-mailbox batch.

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Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:
Also... if you are going to be the administrator for your Office365 service, you need to learn how to use it's powershell.

This blog post will help you do that:
IT_FanaticAuthor Commented:
Wait so your telling me I have to stick to the 2 at a time out of 44 mailboxes? This will take about a year to complete
Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:
Actually... I just took a look and see that the recommendation by acbrown2010 is somewhat correct.

MigrationWiz will actually do that change for you if you modify the Advanced Options of the connector:

(I haven't used MigrationWiz in over a year because I've found that the built-in migration tools have been working well)
Adam BrownSr Solutions ArchitectCommented:
Well, Migwiz won't set the permissions for you. You have to do that manually. You also have to set Migwiz to use that feature for it to do so.
IT_FanaticConnect With a Mentor Author Commented:
I set the permissions. I called microsoft and they said theres just to many mailboxes and they are also very large. So the server will only migrate a few to control the  Throttling
IT_FanaticAuthor Commented:
I also selected my comment because I contacted Microsoft and they verified the issue.
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