Exchange Registry Key Missing (Outlook 2016)

Mike00 236

Hi,

I have come across and issue with Exchange Hybrid where the Outlook client prompts for credentials after migration. The fix detailed in the article below resolves the issue.

https://learn.microsoft.com/en-us/outlook/troubleshoot/authentication/outlook-prompt-password-modern-authentication-enabled

However, a lot of the Outlook clients seem to be missing the HKCU\Software\Microsoft\Exchange key all together and I cannot work out why some have it and others do not. There is nothing on the internet explaining why this issue occurs. Has anyone come across this before?

Thanks,

Mike.

3 answers

Yuki Sun-MSFT 40,856 Reputation points

2020-10-12T02:56:52.673+00:00

Hi Mike,

However, a lot of the Outlook clients seem to be missing the HKCU\Software\Microsoft\Exchange key all together and I cannot work out why some have it and others do not.

I've tried to search around but cannot find a good explanation for this as well. Based on my experience, it's not uncommon that some registry keys are not existent on clients side and we need to manually add the key when need to apply certain settings. But honestly this doesn't explain why this key is only missing on some clients in your environment.

Given this, would you please have a look at the path below on one of the affected clients and see if the "Exchange" key is located there?
HKEY_CURRENT_USER\Software\Policies\Microsoft

If it's not there either, I'd suggest just going ahead to manually add the registry keys required.

Update:

Current status:
Manually creating the registry doesn't work. Recreating Outlook profiles works, but there are a large number of users in the org.

Suggestion:
Recreate Outlook profile for all users via GPO. For detailed steps, you can refer to the link below:
How to create a new Outlook profile for all users in the domain
(Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)

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Mike00 236 Reputation points

2020-10-12T02:59:29.533+00:00

Hi YukiSun,

Thanks for the response, however adding the keys manually does not work. I did try this and when the keys are added manually the issue persists and user is prompted for credentials.

Also the Exchange key does not exist under the HKEY_CURRENT_USER\Software\Policies\Microsoft location as suggested.

Thanks,

Michael.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-13T00:13:56.8+00:00

Hi Michael,

Are the users all located in the same environment?
Have you tried creating a new Outlook profile for one of the users in question and check the results?

Mike00 236 Reputation points

2020-10-13T00:15:58.43+00:00

Hi YukiSan,

Yes all users are in the same environment on the same version of Exchange. A re-profile does fix the issue but this is not a feasible solution for a large environment, which is why I would like to find a solution to the problem.

Michael.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-13T00:16:18.6+00:00

Besides, let's say User A is working fine with the proper registry entries, User B is prompted for credentials and lack of the Exchange key, please have a go using the steps below and see if it can help:
Important: Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

Find the Exchange registry entry on User A's machine, right click on it and choose Export to export the Exchange entry into a .reg file:

Copy the .reg file to User B's machine, double click to import it and check the result.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-13T00:21:58.563+00:00

Hi Michael,

A re-profile does fix the issue but this is not a feasible solution for a large environment

So does the Exchange registry appear after recreating the profile?

Mike00 236 Reputation points

2020-10-13T00:29:38.907+00:00

Yes it does. Just going to be a lot of work if we have to tell ~5000 users to re-create their profiles. I would like a way to automate the fix if possible.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-13T02:40:10.42+00:00

Hi @Mike00 ,

I just tested in my lab by deleting the entire Exchange entry and then creating a new Outlook Profile, the Exchange registry below got created with some subkeys:

Taking the "AlwaysUseMSOAuthForAutoDiscoverinto" registry key into consideration, would you please try testing on one machine by importing the reg file attached (Please change the file extension to ".reg" )and check the result?

exchangeentry.txt

Mike00 236 Reputation points

2020-10-14T05:29:18.657+00:00

Hi YukiSan,

Unfortunately this did not work. After adding the registry keys manually Outlook seems to just delete them again after a restart of the client.

Michael.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-15T00:25:25.183+00:00

Hi Michael,

Thanks for the feedback. This seems weird.. May I know the build number of the affected Outlook clients? You can check it via File > Account > About Outlook and then compare it with the Outlook version on the normal machines.

Also it's suggested to check if the Outlook clients in question have any shared third-party add-ins. You can view the list of add-ins by going to File > Options > Add-ins > Go.

Furthermore, to eliminate the impact of third party application and services, would you please try to test on one client by performing a Windows clean boot and see if the registry can be imported and retained.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-15T01:02:31.443+00:00

Hi Michael,

Considering that "a re-profile does fix the issue" and it could be quite difficult and time-consuming to sort out the Exchange registry issue, personally I would recommend recreating Outlook profiles for all users via Group Policy as a workaround.
I have updated my initial reply to include a link with the step-by-step instructions on how to create the script and GPO, see the "Update" section in my initial post. I've followed the steps to test in my lab and it did work on my end. You can have a check and start it with a small number of users like in a smaller OU and see how it goes. Hope you can find this helpful.

Mike00 236 Reputation points

2020-10-15T23:15:45.717+00:00

Thanks for the response, however doing this for an environment of up to 10,000 staff means that all of these people will need to re-download email and have to manually add delegate mailboxes to the profile (no auto-mapping enabled). This is a huge task to undertake. My preference would be to understand why the problem has occurred and resolve it instead of re-creating profiles in bulk.

Any other suggestions would be much appreciated.

Mike.

Yuki Sun-MSFT 40,856 Reputation points

2020-10-19T07:43:20.617+00:00

Hi Mike,
Okay, that's fully understandable. As this issue only occurs to part of the users, we may then try to find out if there's any difference between them that makes the Exchange registry only available to a partial of the users. As mentioned earlier, would you please check the build number of the Outlook clients via File > Office Account > About Outlook and see if all users are running the same version?
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EXCH Admin 1 Reputation point

2021-04-27T21:28:28.637+00:00

Did the OP ever find the answer to this? I am having the same issue.
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GrA 0 Reputation points

2023-07-28T14:45:31.2266667+00:00

Try opening regedit as the user not as admin.
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