Display name change not removing/merging legacy ID in Outlook Calendar desktop client

Question

Display name change not removing/merging legacy ID in Outlook Calendar desktop client

Aaron B 0

Hello,

We recently began syncing our hris to AD for emp data. This caused some sn/givenname changes. We run a hybrid environment. The issue is in desktop Outlook client, in Calendar. The executive team has a "Team" in Calendar and users are listed with display name. This was also updated with the sn/givenname. We are seeing both name sets in the client. I have tried disabling Exchange cache mode.

*Jonathan Doe

*John Doe

Thank you,

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1 answer

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Answer 1

Michelle-N 20,735 Microsoft External Staff Moderator

Hi @Aaron B

Based on your description, I understand that you recently automated your HRIS synchronization into your on-premises Active Directory to update employee data, which modified several users' surname (sn) and given name (givenName) values. Your infrastructure runs in a Hybrid deployment. The issue is that inside the desktop Outlook client's Calendar interface, the executive team has a built-in "Team" calendar group where users are now showing up with dual entries—displaying both their old and new name sets simultaneously. This persistence occurs even after you attempted to isolate the issue by disabling Exchange Cached Mode.

Reference: Administering the offline address book in Outlook

To help narrow down the cause, does it show the correct single updated name inside the Outlook Web App (OWA)? Please check the following steps:

-Re-Generate and Force-Download the Offline Address Book (OAB)

Microsoft documentation notes that when Outlook runs in Cached Exchange Mode, it relies on local .oab address files rather than querying the live Global Address List (GAL) on every click. Even if you toggled Cached Mode off temporarily, Outlook often retains active pointer files in the background until forced to rebuild.

Please ensure that the Exchange hybrid infrastructure has completed its daily OAB generation cycle since the HRIS sync ran. Force a manual update in the Outlook Desktop client:

Go to the Send / Receive tab on the ribbon > Click Send/Receive Groups and select Download Address Book... > Uncheck “Download changes since last Send/Receive” to force a full data block pull, choose your Global Address List, and click OK.

-Rebuild the Calendar Group Shortcut

Calendar Groups (like the executive "Team" view) inside Outlook do not pull dynamically from the Active Directory structure in real-time. Instead, they act as static shortcuts that capture a snapshot of a user's displayName and routing string at the exact moment the group was created.

When you changed the sn/givenname schema attributes, Outlook created a new snapshot for the updated account identity, but the local calendar folder structure failed to dump the historical snapshot link, resulting in the duplicate "both name sets" view.

-Clear stale Outlook name cache if the old name still appears

Outlook maintains an AutoComplete/nickname cache that includes display names and address-related values for people you have previously addressed messages to. If the old name appears when resolving recipients or in meeting-related fields, remove the individual stale AutoComplete entry or clear the AutoComplete cache from File > Options > Mail > Empty Auto-Complete List.

Please let me know more details.

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Aaron B 0 Reputation points

2026-07-13T18:52:34.73+00:00

Thank you for the response.

"To help narrow down the cause, does it show the correct single updated name inside the Outlook Web App (OWA)?"

It does not.

Since it does not, I take away I should update the GAL and empty the auto complete list? Is that all that is required to rebuild the calendar group structure?

To note, the hris has been syncing and these changes have been in place for 30 days.
Michelle-N 20,735 Reputation points Microsoft External Staff Moderator

2026-07-14T14:52:09.16+00:00

Hi @Aaron B

Thanks for confirming that the issue also appears in Outlook on the web.

If the old/duplicate name is visible in OWA as well, then clearing the Outlook desktop cache, downloading the OAB, or emptying AutoComplete is probably not sufficient by itself. Microsoft’s OAB troubleshooting guidance notes that if the expected change is not present in the GAL when checked through Outlook Web App, that change will not replicate correctly to the Offline Address Book either. So the first step should be to confirm that the recipient object is correct in the source directory and Exchange address list, not only on the Outlook client side.

In a hybrid environment where HRIS updates are flowing into on-premises AD, I would suggest checking whether both the old and new names are resolving as separate recipient objects, contacts, mail users, or stale address list entries. For example, search both name variants in Exchange/Exchange Online recipient views and confirm whether there is only one recipient object and that its DisplayName, Name, alias, primary SMTP address, and proxy/X500 addresses are expected.
Michelle-N 20,735 Reputation points Microsoft External Staff Moderator

2026-07-15T09:45:56.42+00:00

Hi @Aaron B

Is there any update from you?

If yes, please feel free to let me know.
Aaron B 0 Reputation points

2026-07-16T21:21:09.88+00:00

Hello,

Apologies if I wasnt clear. The issue is NOT in OWA. It is also NOT in "New" Outlook. I'm no pro, but this seems to be an appdata cache issue, but I dont know where. I have disabled Exchange Cache mode. I have also cleared the following:
%localappdata%\Microsoft\Outlook\RoamCache
%localappdata%\Microsoft\Outlook\HubAppFileCache

Please let me know what I can try next.
Michelle-N 20,735 Reputation points Microsoft External Staff Moderator

2026-07-17T14:05:33.0133333+00:00

Hi @Aaron B

Thanks for clarifying. Since the issue does not reproduce in OWA or New Outlook, this does sound more likely related to the Classic Outlook local profile/cache rather than the mailbox itself.

As a next step, I would suggest renaming the entire %LOCALAPPDATA%\Microsoft\Outlook\RoamCache folder to old_RoamCache instead of only clearing its contents, then restart Outlook and let it recreate the folder.

If the issue involves add-ins or web-based Outlook components, also clear %LOCALAPPDATA%\Microsoft\Office\16.0\Wef and %USERPROFILE%\AppData\Local\Microsoft\Outlook\HubAppFileCache.

If the issue still persists, rebuild the local OST by closing Outlook, renaming the affected .ost file under %LOCALAPPDATA%\Microsoft\Outlook, and then reopening Outlook to let it resync. If that still does not help, create a new Outlook profile from Control Panel > Mail > Show Profiles and test with a fresh profile.

Also, if this involves shared mailboxes or shared folders, it may be worth testing with shared folder caching disabled, as shared folder data can also be stored in the local OST.
Aaron B 0 Reputation points

2026-07-17T14:33:10.51+00:00

I greatly appreciate your support and responses. I completed the items below, in this order.

ren- %LOCALAPPDATA%\Microsoft\Outlook\RoamCache

clear - %LOCALAPPDATA%\Microsoft\Office\16.0\Wef and %USERPROFILE%\AppData\Local\Microsoft\Outlook\HubAppFileCache

ren - all ost and nst files in %USERPROFILE%\AppData\Local\Microsoft\Outlook\

clear - Mail profile

created a new "OutlookFresh"

opened Outlook client and allowed sync

Same issue. I logged in to OWA and confirmed, the issue does not exist via web.
Michelle-N 20,735 Reputation points Microsoft External Staff Moderator

2026-07-20T14:00:36.5466667+00:00

Hi @Aaron B

Thank you for the update. After looking into this further, it appears that the best option at this point would be to create a support ticket through the Entra Admin Center, where the engineering team will be able to provide the most appropriate assistance. Thank you for your patience throughout this process.