Troubleshooting “Task List Not Found” in SharePoint Workflows

The “Task List Not Found” error occurs when a SharePoint workflow cannot locate the associated Task List required for workflow actions such as approvals, task assignments, or status tracking. This can happen if the task list has been deleted, renamed, moved, or corrupted. Below is a detailed, step-by-step guide to diagnose and resolve the issue.

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Step 1: Verify the Existence of the Task List

1. Navigate to Site Contents:
   • Open SharePoint and go to the site where the workflow is configured.
   • Click on “Site Contents” and look for a list named “Workflow Tasks”, “Tasks”, or any custom task list.
2. Check for Custom Task List Name:
   • Some workflows use a custom task list instead of the default Workflow Tasks.
   • In SharePoint Designer, check which task list is associated with the workflow.
3. Manually Open the Task List:
   • If the task list is found in Site Contents, click on it and ensure it loads correctly.
   • If you receive an error while opening the task list, it may be corrupted or have permission issues.

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Step 2: Check If the Task List Was Renamed

1. In Site Contents, look for any list that was recently renamed.
2. If the task list was renamed, you need to update the workflow with the correct name:
   • Open SharePoint Designer.
   • Locate your workflow under Workflows > Your List/Library.
   • Check the task list name in the workflow settings.
   • Update the task list reference to match the new name.

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Step 3: Verify Workflow Association with Task List

1. Open SharePoint Designer.
2. Locate the affected workflow and go to Workflow Settings.
3. Check the Task List Association:
   • Ensure that a valid task list is assigned.
   • If no task list is assigned, select an existing one or create a new one.
4. Save and Republish the workflow.

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Step 4: Restore a Deleted Task List (If Applicable)

If the task list was accidentally deleted, you can restore it from the SharePoint Recycle Bin:

1. Go to Site Settings > Recycle Bin.
2. Look for the deleted Tasks list.
3. Select it and click Restore.
4. Once restored, check if the workflow functions correctly.

If the task list is permanently deleted, proceed to Step 5 to recreate it.

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Step 5: Recreate the Missing Task List

If the original task list is missing or corrupted, you must create a new one:

For SharePoint 2010/2013 Workflows (Using SharePoint Designer):

1. Open SharePoint Site Contents.
2. Click “New” > “App”.
3. Select “Tasks” or “Workflow Tasks”.
4. Name it “Workflow Tasks” or any preferred name.
5. Open SharePoint Designer and go to the workflow settings.
6. Change the Task List Reference to point to the new list.
7. Republish the workflow and test it.

For Power Automate Workflows:

1. Open Power Automate Portal.
2. Locate your workflow under My Flows.
3. If the workflow uses a Planner task list or a custom SharePoint list, ensure the correct list is referenced.
4. Update the workflow to use the newly created task list.

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Step 6: Verify Permissions on the Task List

1. Go to Site Contents > Task List.
2. Click on List Settings > Permissions for this list.
3. Ensure the workflow owner and participants have the following permissions:
   • Contribute (to create/edit tasks)
   • Edit (to update task statuses)
   • Full Control (for workflow admins)

If the workflow runs under a system account, ensure it has access to the task list.

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Step 7: Check for List Corruption

If the task list exists but workflows fail to access it, the list may be corrupted.

1. Try manually adding a task to the list.
2. If you receive an error, the list is likely corrupted.
3. Create a new task list (Step 5) and reassociate the workflow.

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Step 8: Review SharePoint Logs (For On-Premises Users)

If you are using SharePoint Server (on-premises), check the ULS logs for errors related to task lists:

1. Open SharePoint Management Shell as Administrator.
2. Run the following command to filter logs: Get-SPLogEvent | Where-Object { $_.Message -like "*task list*" }
3. Look for messages indicating missing lists, permission issues, or service failures.

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Step 9: Re-Publish or Recreate the Workflow

If all else fails, try recreating the workflow:

1. Open SharePoint Designer or Power Automate.
2. Save a backup of the existing workflow.
3. Create a new workflow with the same logic but reference a new task list.
4. Publish and test the workflow.

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