1. Check the configuration for your GitLab SAML app and ensure that **Name identifier value** (NameID) points to `user.objectid` or another unique identifier. This will match the `extern_uid` used on GitLab.
[Provisioning users and groups to applications that support SCIM](https://docs.microsoft.com/en-us/azure/active-directory/app-provisioning/use-scim-to-provision-users-and-groups#provisioning-users-and-groups-to-applications-that-support-scim) section in Azure's SCIM setup documentation.
You can then test the connection by clicking on **Test Connection**. If the connection is successful, be sure to save your configuration before moving on. See below for [troubleshooting](#troubleshooting).
1. Determine how GitLab will uniquely identify users.
- Use `objectId` unless users already have SAML linked for your group.
- If you already have users with SAML linked then use the `Name ID` value from the [SAML configuration](#azure). Using a different value will likely cause duplicate users and prevent users from accessing the GitLab group.
1. Save your changes. For reference, you can view [an example configuration in the troubleshooting reference](../../../administration/troubleshooting/group_saml_scim.md#azure-active-directory).
Once synchronized, changing the field mapped to `id` and `externalId` will likely cause provisioning errors, duplicate users, and prevent existing users from accessing the GitLab group.
As long as [Group SAML](index.md) has been configured, prior to turning on sync, existing GitLab.com users can link to their accounts in one of the following ways, before synchronization is active:
- By updating their *primary* email address in their GitLab.com user account to match their identity provider's user profile email address.
- By following these steps:
1. Sign in to GitLab.com if needed.
1. Click on the GitLab app in the identity provider's dashboard or visit the **GitLab single sign on URL**.
1. Click on the **Authorize** button.
New users and existing users on subsequent visits can access the group through the identify provider's dashboard or by visiting links directly.
For role information, please see the [Group SAML page](index.md#user-access-and-management)
### Blocking access
To rescind access to the group, we recommend removing the user from the identity
provider or users list for the specific app.
Upon the next sync, the user will be deprovisioned, which means that the user will be removed from the group. The user account will not be deleted unless using [group managed accounts](index.md#group-managed-accounts).
When testing the connection, you may encounter an error: **You appear to have entered invalid credentials. Please confirm you are using the correct information for an administrative account**. If `Tenant URL` and `secret token` are correct, check whether your group path contains characters that may be considered invalid JSON primitives (such as `.`). Removing such characters from the group path typically resolves the error.
### Message: "SAML authentication failed: Email has already been taken"
It is expected for the app's logs to show this error for any existing user until they sign in for the first time. GitLab will not allow multiple accounts to have the same email address.
### How do I diagnose why a user is unable to sign in
The **Identity** (`extern_uid`) value stored by GitLab is updated by SCIM whenever `id` or `externalId` changes. Users won't be able to sign in unless the GitLab Identity (`extern_uid`) value matches the `NameId` sent by SAML.
This value is also used by SCIM to match users on the `id`, and is updated by SCIM whenever the `id` or `externalId` values change.
It is important that this SCIM `id` and SCIM `externalId` are configured to the same value as the SAML `NameId`. SAML responses can be traced using [debugging tools](./index.md#saml-debugging-tools), and any errors can be checked against our [SAML troubleshooting docs](./index.md#troubleshooting).
### How do I verify user's SAML NameId matches the SCIM externalId
Group owners can see the list of users and the `externalId` stored for each user in the group SAML SSO Settings page.
Alternatively, the [SCIM API](../../../api/scim.md#get-a-list-of-saml-users) can be used to manually retrieve the `externalId` we have stored for users, also called the `external_uid` or `NameId`.
If GitLab's `externalId` doesn't match the SAML NameId, it will need to be updated in order for the user to log in. Ideally your identity provider will be configured to do such an update, but in some cases it may be unable to do so, such as when looking up a user fails due to an ID change.
Fixing the fields your SCIM identity provider sends as `id` and `externalId` can correct this, however we use these IDs to look up users so if the identity provider is unaware of the current values for these it may try to create new duplicate users instead.
If the `externalId` we have stored for a user has an incorrect value that doesn't match the SAML NameId, then it can be corrected ine on or two ways.
One option is to have users can be delinked and relink following details in the ["SAML authentication failed: User has already been taken"](./index.md#message-saml-authentication-failed-user-has-already-been-taken) section. Additionally, to unlink all users at once, remove all users from the SAML app while SCIM is still turned on.
Another option is with the manual use of the SCIM API.
The [SCIM API](../../../api/scim.md#update-a-single-saml-user) can be used to manually correct the `externalId` stored for users so that it matches the SAML NameId. You'll need to know the desired value that matches the `NameId` as well as the current `externalId` to look up the user.
It is then possible to issue a manual SCIM#update request, for example:
It is important not to update these to incorrect values, since this will cause users to be unable to sign in. It is also important not to assign a value to the wrong user, as this would cause users to get signed into the wrong account.
Individual users can follow the instructions in the ["SAML authentication failed: User has already been taken"](./index.md#i-need-to-change-my-saml-app) section.
Alternatively, users can be removed from the SCIM app which will delink all removed users. Sync can then be turned on for the new SCIM app to [link existing users](#user-access-and-linking-setup).
