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Good day
Having an issue with outlook 365 application on Windows 10 PC with error 1001 and the inbox is not syncing. Please could someone let me know why this is, I have tried looking online but can't seem to find much information on this error. What I found is possible issue with not enough memory but when I run task manager there is no issue with performance, memory at about 50%. When I login to Webmail, emails are working fine, so seems to be mailbox/application issue.
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Hi BradleyWilson-8905,
Are you using a Microsoft authenticator or two step authentication for your Microsoft Applications/Outlook?
On the other hand, if we use a third party security software in our machine, that may interfere in software algorithms and performance.
Please update with your findings!
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Hi @Anonymous ,
Just checking to see if there are any updates. Did you get a chance to check the suggestions provided.
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i solved only deleting a windows registry key:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities
then i rebooted the pc and after the logon always works fine.
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I had this issue as well in a terminal server environment. I did cleanups of HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities , C:\Usersyourusername\AppData\Local\Microsoft\ OneAuth and IdentityCache folders
this did not resolve the issue, Contacted MS support and thy just said to blow away the user profile, this resolved the issue. kind of sad the problem had to bit with such a large stick.
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OK for me, thanks !
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Had the exact same issue. None of these steps helped me.
Situation: We've got 3 terminalserver and only two of them were in use.
"Workaround": I have registered the faulty Outlook user on the second empty terminal server. After only this user was logged on to this server, I started the online repair of Office. For whatever reason, this solution or workaround worked.
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A note for anyone coming across this thread, it seams to have multiple causes. Just a simple reboot fixed the issue for me.
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We are only having this issue on accounts accessed through RDS/RDP. We suspect Windows server to have problem releasing licence after some connections, then running out of licences.
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Jean, I am also on RDS and in my case it is not licensing.
Many of the prior comments here are not relevant to Servers and RDS.
Please see my comment below made on 26Sep2023 regarding running Microsoft Support and Recovery Assistant (SARA) as administrator. I was suffering this issue on 2 RDS servers for only 2 users, not for everyone. I tried many fixes suggested in user forums an nothing worked for me. I kept trying to target just those 2 users. Finally, out of desperation, I decided to just run SARA. It did not work when ran as the user. So I thought I'd try running it as administrator while on the same RDS server as the user who was currently logged on, and I was shocked it worked and I have no clue what it did to fix it. No other users have reported anything adverse (well, except for one time SARA removed the "shared computer activation" which I explain how to fix in that 26Sep2023 posting below.
I was surprised to find that Microsoft SARA fixed this for me (Microsoft Support and Recovery Assistant):
As the administrator, I logged onto the RDS server where the user was encountering the problem, while the user was still logged on (not sure if she needed to be logged on, but her registry keys wouldn't be available otherwise) and I downloaded [ https://learn.microsoft.com/en-us/microsoft-365/troubleshoot/authentication/automatic-authentication-fails ]
I ran it and it did its thing.
I then went back to the user's session and I was shocked to find that the 1001 error no longer came up! I did this on another RDS server where another user had it and the error went away for that user too.
! HOWEVER, I ran it SARA another time and it removed our Office’s "Shared Computer Activation!" No one could log into MS Office after that. I simply had to add String "SharedComputerLicensing=1 back to "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration" and all went back to normal again.
Note that there have been many, many, many reports of issues with Microsoft "Modern Authentication" (MA) for which numerous anecdotal solutions exist. But many times these suggested solutions only sometimes work. Microsoft has verified in their test environment that there is something wrong with MA[1], but this issue has been outstanding since at least 2020.
This 1001 error, for me, is the first time I've encountered it. I am not certain it was brought on by MA or by my attempted fixes suggested in user forums for recurring MA issues.
([1]https://answers.microsoft.com/en-us/msoffice/forum/all/office-365-needs-every-login-on-rds-new/2e8bf47c-eb35-4c48-a8e3-a6ecaccbafa6)
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We found that by "revoking multifactor authentication sessions " in Entra ID instantly fixed the issue.
cheers