Outlook 365 application error 1001, mail is not syncing

Anonymous

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.

workforce45 631 Reputation points

2022-12-28T18:45:34.79+00:00

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!
Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2023-01-02T07:51:45.52+00:00

Hi @Anonymous ,

Just checking to see if there are any updates. Did you get a chance to check the suggestions provided.
Francesco Porta 30 Reputation points

2023-09-04T12:24:22.33+00:00

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.
OG-ACS 10 Reputation points

2023-09-14T03:06:29.2866667+00:00

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.
Matthieu CRIBIER 0 Reputation points

2023-10-05T09:39:03.8066667+00:00

OK for me, thanks !
Dominic Kägi 5 Reputation points

2024-07-23T11:55:05.55+00:00

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.

14 answers

Yuki Sun-MSFT 41,146 Reputation points Microsoft Vendor

2022-12-29T03:14:29.107+00:00

Hi @Anonymous ,

Is this a suddenly occurred issue?
Does it affect others in the same environment as you?

In case it's due to any corrupted configurations of the existing Outlook profile, please try creating a new Outlook profile and then add the email account again to see if it can work as expected. For steps of creating a new Outlook profile, you may refer to Overview of Outlook e-mail profiles-Create a new profile. Also remember to configure Outlook to prompt you to choose a profile when started so that you can choose the new profile next time.

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A, Yosi 1 Reputation point

2023-06-08T18:52:06.6233333+00:00
Thanks for your help. This is what helped me:

First I went to Credential Manager --> Windows Credentials --> Removed anything with Office.

Opened Word --> Account --> Sign Out & Back in (to all Microsoft Apps)

Outlook opened fine.

Hope this helps!
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Jean-Yves Hemlin 0 Reputation points

2023-09-25T18:06:13.7633333+00:00

I never found anything with "Office" in its name there.

Teams, OneDrive, SSO device but never office
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Lauren Reed 0 Reputation points

2023-07-05T19:06:34.5733333+00:00

I had the same problem and a quick repair through the control panel fixed it.
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Michael Speights 20 Reputation points

2023-07-25T12:24:54.9133333+00:00

Does GoDaddy services has something to do with this error?
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Juanito Emia 0 Reputation points

2023-07-26T23:42:26+00:00

I had this issue as well. It was resolved by doing the steps below.

I created a new Outlook profile.

Restarted Machine.

It worked after I signed back on to Outlook.

Jean-Yves Hemlin 0 Reputation points

2023-09-25T18:07:52.06+00:00

Unlikely. I manage over 500 users and we're not with GoDaddy yet we have this bug affecting users daily. Some users seemed to be more affected than others.
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Russell T 0 Reputation points

2023-08-23T15:10:12.7233333+00:00

Creating a new profile and restarting the machine worked for me
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Outlook 365 application error 1001, mail is not syncing

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