## Symptoms Migration task creation failed with an error: Failed to create role. ## What it means When you create a migration task with cross\-service authorization, DMS automatically creates a policy and attaches it to the ServiceRoleforDMSAccessTOS role. This policy grants the role permission to read from the source bucket and write to the destination bucket, allowing DMS to access resources in TOS through the ServiceRoleforDMSAccessTOS role. Each ServiceRoleforDMSAccessTOS role can be attached to a maximum of 10 custom policies. For details, see [Usage Restrictions](https://www.volcengine.com/docs/6257/1285191). If you create more than 10 migration tasks using cross\-service authorization, exceeding the policy attachment limit for ServiceRoleforDMSAccessTOS, policy attachment will fail and the task creation will fail with an error: Failed to create role. ## Solution ### Option 1: Delete completed tasks After deleting migration tasks in cross\-service authorization mode, the policy created for that task will be deleted automatically. You can delete completed tasks to free up ServiceRoleforDMSAccessTOS role quota for associating new task policies. Steps: Log in to [DMS Console](https://console.volcengine.com/dms), go to the **Migration Task List** page, and click **Delete** under the **Action** column of the target migration task. In the pop\-up dialog box, click **Delete**. ### Option 2: Unbind the ServiceRoleforDMSAccessTOS role and policies You can unbind the ServiceRoleforDMSAccessTOS role and policies to free up quota for associating new task policies. After unbinding the ServiceRoleforDMSAccessTOS role and policies, you can delete the policies. Steps: 1. Unbind the ServiceRoleforDMSAccessTOS role and policies. 1. Log in to [DMS Console](https://console.volcengine.com/dms). 2. Click the account avatar in the top right corner and select **Access Control** from the dropdown menu. 3. In the left navigation pane, select **Identity Management** \> **Role**. 4. On the **Role** page, search for **ServiceRoleforDMSAccessTOS**. Once found, click **ServiceRoleforDMSAccessTOS.** 5. Under the **Global Permissions** tab, click **Remove** to the right of the target policy.

tip

Policies automatically created by DMS are named in the format DMS_TaskName. You can locate a policy by the name of its corresponding task.

6. In the dialog box that appears, click **Remove**. 2. Delete policy. 1. In the left navigation pane, click **Policy Management**. 2. On the **Policy List** page, search for the policy name that was removed in step 1. Once you find the target policy, in the **Action** column, click **Delete**. 3. In the dialog box that appears, click **Delete**.

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