Troubleshoot EUSERNOTFOUND error during backup of Exchange Online and OneDrive
This article applies to:
- Product edition: inSync Cloud
Problem description
During the backup of the Microsoft 365 data for Exchange Online and OneDrive apps, inSync shows an error EUSERNOTFOUND.
This article discusses the scenarios arising with different user configurations on Exchange Online and OneDrive and provides the resolution steps for each.
Cause
By default OneDrive is mapped to the Username parameter in Microsoft 365, which cannot be changed. Exchange online, on the other hand can either match the email to the Username or it can be separate from the username. If the email address does not match the username, the username is added as an email alias under Exchange Online. You cannot remove the alias entry for the username from Exchange online.
Scenario-1: Email address and UPN is same for inSync user and Microsoft 365
| inSync email ID | AD/LDAP name | ID to access user accounts | Exchange online email/SMTP | Exchange Online alias/SMTP | OneDrive UPN (User Principal Name) | Exchange Online Backup status | OneDrive Backup status |
|---|---|---|---|---|---|---|---|
| Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | inSync email | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Backup successful | Backup successful |
| Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | UPN | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Backup successful | Backup successful |
Since the user email ID and UPN is same in inSync and Microsoft 365, you can match either the email ID or UPN against that of Microsoft 365 using the following steps:
To change these settings:
- On the inSync Management Console menu bar, click Data Sources > Microsoft 365.
- On the Overview page, click
and then click Settings. The Cloud App Settings dialog box appears. By default, the Access user accounts using is configured to inSync Email ID is selected.
- Check the backup status in inSync for Exchange Online and OneDrive where backup is successfully completed.
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- Switch the Access user accounts using setting to AD Attribute and set it to User Principal Name (UPN).
inSync backup succeeds as email address and UPN is same for inSync and Microsoft 365.
Scenario-2: Email address and UPN is different for the inSync user
When the email address and UPN are different for an inSync user, but same for corresponding Microsoft 365 user, you can match either the email ID or UPN against Microsoft 365 to validate the user.
| inSync email ID | AD/LDAP name | ID to access user accounts | Exchange online email/SMTP | Exchange Online alias/SMTP | OneDrive UPN (User Principal Name) | Exchange Online Backup status | OneDrive Backup status |
|---|---|---|---|---|---|---|---|
| Brian.C@druva365.tk | Brian.Connor@druva365.tk | inSync email | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | EUSERNOTFOUND | EUSERNOTFOUND |
| Brian.C@druva365.tk | Brian.Connor@druva365.tk | UPN | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Backup successful | Backup successful |
To configure these settings:
- On the inSync Management Console menu bar, click Data Sources > Microsoft 365.
- On the Overview page, click
and then click Settings. The Cloud App Settings dialog box appears. By default, the Access user accounts using is configured to inSync Email ID is selected.
Since, Email address in inSync is Brian.c@druva365.tk and username/email in Microsoft 365 is Brian.connor@druva365.tk, backup fails for both OneDrive as well as Exchange Online.
- Switch the Access user accounts using setting to AD Attribute and set it to User Principal Name (UPN).
Since, AD/LDAP name in inSync is Brian.connor@druva365.tk and username/email in Microsoft 365 is Brian.connor@druva365.tk, inSync Backup will be successfully completed as inSync will able to find user in Microsoft 365 using UPN.
Scenario 3: Username and Email Address are different in inSync and Microsoft 365
In this scenario, the inSync email ID matches the Microsoft 365 email address. Similarly, the inSync AD/LDAP username matches the Username in Microsoft 365. However, the email address and username do not match each other in both inSync and Microsoft 365.
| inSync email ID | AD/LDAP name | ID to access user accounts | Exchange online email/SMTP | Exchange Online alias/SMTP | OneDrive UPN (User Principal Name) | Exchange Online Backup status | OneDrive Backup status |
|---|---|---|---|---|---|---|---|
| Brian.C@druva365.tk | Brian.Connor@druva365.tk | inSync email | Brian.C@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Backup successful | EUSERNOTFOUND |
| Brian.C@druva365.tk | Brian.Connor@druva365.tk | UPN | Brian.C@druva365.tk | Brian.Connor@druva365.tk | Brian.Connor@druva365.tk | Backup successful | Backup successful |
To validate the user from inSync, you can match either the email ID or UPN with the one in Microsoft 365.
To configure these settings:
- On the inSync Management Console menu bar, click Data Sources > Microsoft 365.
- On the Overview page, click
and then click Settings. The Cloud App Settings dialog box appears. By default, the Access user accounts using is configured to inSync Email ID is selected.
Since email address for inSync user brian.c@druva365.tk and Exchange mailbox is same, the backup is successful.
Since OneDrive is only mapped to UPN, its authentication fails when it is validated against inSync email.
- Switch the Access user accounts using setting to AD Attribute and set it to User Principal Name (UPN).
Here, AD/LDAP name in inSync is Brian.connor@druva365.tk and email aliases in Exchange Online is Brian.connor@druva365.tk, inSync Backup succeeds as inSync is able to find the user in Microsoft 365 using email aliases.
Since, AD/LDAP name in inSync is Brian.Connor@druva365.tk and Username in OneDrive is Brian.Connor@druva365.tk, inSync backup succeeds as inSync is able to find the user in Microsoft 365 using email aliases.
For more information, see Cloud Apps integration error messages.