Login Failed for User '

Question

Login Failed for User '

Shweta Singh 0

Encountering the error "Login failed for user '

Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-09T16:54:46.8733333+00:00

Hi @ Shweta Singh

Could you please elaborate on the issue and please share the details asked in the private message.
Nandan Hegde 36,151 Reputation points MVP Volunteer Moderator

2025-06-10T04:23:02.64+00:00

Are you trying to access the database via SSMS?
Shweta Singh 0 Reputation points

2025-06-10T04:25:51.4366667+00:00

Hi @Sai Raghunadh M , we are intermittently getting this error: Login failed for user '<token-identified principal>'. in production when trying to fetch data from database. Could u pls help on what could be the issue here
Shweta Singh 0 Reputation points

2025-06-10T04:48:51.7433333+00:00

@Nandan Hegde No, we are accessing the database through application code using entity framework.
Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-10T13:34:18.0166667+00:00
Hi @ Shweta Singh

Thank you for reaching out. The error "Login failed for user '<token-identified principal>'" typically occurs when using Managed Identity or Azure Active Directory authentication.

Here are some potential solutions:

Verify User Existence in Database:

If using Azure AD authentication, ensure the user is created within the database:

CREATE USER [******@domain.com] FROM EXTERNAL PROVIDER;

Assign necessary roles:

ALTER ROLE db_datareader ADD MEMBER [******@domain.com]; ALTER ROLE db_datawriter ADD MEMBER [******@domain.com];

Check Connection String:

If using Managed Identity, confirm that the authentication type is set correctly:

Authentication=Active Directory Managed Identity;

If using Azure AD Password authentication, ensure the correct authentication type is used:

Authentication=Active Directory Password;

Navigate to Azure Portal > SQL Server > Active Directory Admin and confirm an admin is assigned.

In Firewall settings, ensure "Allow Azure services and resources to access this server" is enabled.

Some applications resolve authentication issues by explicitly defining the database in the connection properties.

Please go through these references that might help you:

https://stackoverflow.com/questions/72793296/login-failed-for-user-token-identified-principal-microsoft-sql-server-err

https://www.c-sharpcorner.com/blogs/resolved-login-failed-for-user-tokenidentified-principal

Hope this helps. Do let us know if you any further queries.
Shweta Singh 0 Reputation points

2025-06-11T10:44:33.77+00:00

@Sai Raghunadh M , I checked the above ones which you suggested we already have all of those. Just to have more context, we have an Entity Framework Core DbContext with connection pooling and having an interceptor which fetches the token using DefaultAzureCredential so I can't use Authentication in our connection string.
Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-11T17:12:11.0833333+00:00

Hi @ Shweta Singh

Which error state you are receiving?
18456 state 5 or 18456 state 8?
Shweta Singh 0 Reputation points

2025-06-12T05:18:22.5466667+00:00

We don't get an error state in our logs.
Narendra Pakkirigari 475 Reputation points Microsoft External Staff Moderator

2025-06-13T05:35:26.49+00:00

Hi Shweta Singh,

Could you please share the name of the database you're experiencing along with the exact error message you're encountering with in a private message?
Shweta Singh 0 Reputation points

2025-06-17T10:24:31.97+00:00

Hi @Narendra Pakkirigari , I have shared the db name and exception details in private message. Pls take a look.

1 answer

Your answer

Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-09T16:54:46.8733333+00:00

Hi @ Shweta Singh

Could you please elaborate on the issue and please share the details asked in the private message.
Nandan Hegde 36,151 Reputation points MVP Volunteer Moderator

2025-06-10T04:23:02.64+00:00

Are you trying to access the database via SSMS?
Shweta Singh 0 Reputation points

2025-06-10T04:25:51.4366667+00:00

Hi @Sai Raghunadh M , we are intermittently getting this error: Login failed for user '<token-identified principal>'. in production when trying to fetch data from database. Could u pls help on what could be the issue here
Shweta Singh 0 Reputation points

2025-06-10T04:48:51.7433333+00:00

@Nandan Hegde No, we are accessing the database through application code using entity framework.
Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-10T13:34:18.0166667+00:00

Hi @ Shweta Singh

Thank you for reaching out. The error "Login failed for user '<token-identified principal>'" typically occurs when using Managed Identity or Azure Active Directory authentication.

Here are some potential solutions:

Verify User Existence in Database:

If using Azure AD authentication, ensure the user is created within the database:

CREATE USER [******@domain.com] FROM EXTERNAL PROVIDER;

Assign necessary roles:

ALTER ROLE db_datareader ADD MEMBER [******@domain.com]; ALTER ROLE db_datawriter ADD MEMBER [******@domain.com];

Check Connection String:

If using Managed Identity, confirm that the authentication type is set correctly:

Authentication=Active Directory Managed Identity;

If using Azure AD Password authentication, ensure the correct authentication type is used:

Authentication=Active Directory Password;

Navigate to Azure Portal > SQL Server > Active Directory Admin and confirm an admin is assigned.

In Firewall settings, ensure "Allow Azure services and resources to access this server" is enabled.

Some applications resolve authentication issues by explicitly defining the database in the connection properties.

Please go through these references that might help you:

https://stackoverflow.com/questions/72793296/login-failed-for-user-token-identified-principal-microsoft-sql-server-err

https://www.c-sharpcorner.com/blogs/resolved-login-failed-for-user-tokenidentified-principal

Hope this helps. Do let us know if you any further queries.
Shweta Singh 0 Reputation points

2025-06-11T10:44:33.77+00:00

@Sai Raghunadh M , I checked the above ones which you suggested we already have all of those. Just to have more context, we have an Entity Framework Core DbContext with connection pooling and having an interceptor which fetches the token using DefaultAzureCredential so I can't use Authentication in our connection string.
Sai Raghunadh M 4,640 Reputation points Microsoft External Staff Moderator

2025-06-11T17:12:11.0833333+00:00

Hi @ Shweta Singh

Which error state you are receiving?
18456 state 5 or 18456 state 8?
Shweta Singh 0 Reputation points

2025-06-12T05:18:22.5466667+00:00

We don't get an error state in our logs.
Narendra Pakkirigari 475 Reputation points Microsoft External Staff Moderator

2025-06-13T05:35:26.49+00:00

Hi Shweta Singh,

Could you please share the name of the database you're experiencing along with the exact error message you're encountering with in a private message?
Shweta Singh 0 Reputation points

2025-06-17T10:24:31.97+00:00

Hi @Narendra Pakkirigari , I have shared the db name and exception details in private message. Pls take a look.

Answer 1

Hi Shweta Singh,

Below are the possible reasons why a "Login failed for user" error occur:

The "Login failed for user" error in SQL Server can occur due to a variety of reasons, most of which are tied to authentication settings, permissions, or configuration issues. A common reason is using SQL Server Authentication while the server is configured for Windows Authentication only. In such cases, SQL Server logs an error noting that SQL authentication was attempted on a Windows-only server. Similarly, when users try accessing SQL Server through an Active Directory group, the server must be able to resolve the group membership; issues with domain controllers or cross-domain setups can prevent this. Disabled or nonexistent logins are another frequent cause check the Security\Logins folder in SQL Server Management Studio (SSMS) to confirm.

If the login exists but the password is incorrect, SQL will return a password mismatch error. Problems in the connection string, such as a misspelled server or database name, or pointing to the wrong SQL Server instance, can also trigger login failures. Additionally, if the login’s default database is offline or not accessible, or if the user doesn’t have permission to that database, SQL Server will reject the connection. This is often logged with error 4064. In migrations, contained database users can cause issues if logins were deleted afterward. Moreover, the login may be valid, but if the app isn’t run with administrative privileges (like SSMS not being run as administrator), the login might not succeed.

To resolve these issues, it's important to verify server authentication mode, ensure the login exists and is enabled, check the connection string, confirm database availability, and verify that the user has appropriate permissions. Tools like xp_logininfo can help diagnose group resolution issues, and reviewing the SQL Server Errorlog can provide more detailed context about the specific cause of a login failure.

Request to refer the below document:

https://learn.microsoft.com/en-us/sql/relational-databases/errors-events/mssqlserver-18456-database-engine-error?view=sql-server-ver17#login-failed-for-user-username-or-login-failed-for-user-domainusername

Narendra Pakkirigari 475 Reputation points Microsoft External Staff Moderator

2025-06-16T00:54:18.6233333+00:00

Hi Shweta Singh,

If you’ve already found a solution to this problem, we encourage you to share it with the community. Your experience could help others facing a similar issue.

If anything is unclear or if you need further help, feel free to add a comment below.

Also, please click “Accept Answer” if this helped, so others can find the solution more easily.
Narendra Pakkirigari 475 Reputation points Microsoft External Staff Moderator

2025-06-17T06:16:00.31+00:00

Hi Shweta Singh,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know

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Login Failed for User '

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