@joelau - Wow! Pretty serious issue (Don't wait - Create a ticket with Nintex Support asap!)

Item 1. Your Workflow queue length is very unhealthy (33,783)

More Workflows are being started then being completed.

So much so that the System isn't allowing you to start any new Workflow!!

Item 2. Did you trigger workflow to run when List Items are modified?

This will cause the workflow to run whenever a column value is updated.

When your first WF updates a column value, this will trigger a second WF that updates a column value, that will trigger a third WF ... (a serious cascading effect of triggering workflows)

Item 3. Do you consider your process DONE when the Workflow is not completed?

e.g. you don't wait for a final Approval.

As such your workflow would still be in the Started stage and not the completed stage

Item 4. Check where your workflow is pausing or waiting for next actions.

Let the page to load the complete summary.

My site summary shows Queue Length of 1.

Workflow 001 has 22 started items and 4 completed items. Total of 26 items.

Click the Info icon (highlighted in yellow) - This will show (a) at what stage the workflow is at and (b) how many workflow are in that stage.

If i remove those uncompleted tasks from the Workflow Tasts List, can i resume my workflow?

I think you should wait for Nintex Support advice (Best)

You will need to do your personal evaluation about the removal of uncompleted tasks from the Workflow Tasks List and the impact

Some consideration

1. Is this a live production site? Then its a NO

2. Do you know the impact of deleting those uncompleted task?

3. What is the impact of re-running the workflows again?

For Item 2 and 3, what I meant is - if the workflow doesn't change any data and generated a Report. then you could re-run the workflow again and again. however if the workflow changes data whenever you run it, then use upmost caution if you need to re-run it.

4. Are you able to move the list and workflow to another temporary site? (Best)

Move to Test/Development/Staging server or site. Run workflow. Monitor Queue Health