If you’re working with data transformations in Power Query and make a mistake, you might instinctively reach for Ctrl+Z like you would in Excel.
Unfortunately, that won’t work with Power Query.
Power Query doesn’t have a traditional undo button, but don’t worry – there’s still a straightforward way to reverse your changes.
How to Undo One Step
Suppose you have the query below with five applied steps, and you realize that the last step (Grouped Rows) was a mistake.
To undo this step, simply hover your mouse pointer over the step in the Applied Steps pane and click the X icon that appears next to it.
The step will be deleted immediately, and your data will revert to how it looked before that transformation was applied.
You can also right-click on any step and select “Delete” from the context menu as an alternative to using the X icon.
How to Undo Multiple Steps
Sometimes you need to undo several steps at once.
For example, if you have five applied steps and want to remove the third step along with everything that came after it.
To delete multiple steps:
- Right-click on the step where you want to start deleting (the third step in this example)
- Select “Delete Until End” from the shortcut menu
This will remove the selected step and all subsequent steps in one go.
Instead of permanently deleting steps, you can also click on any previous step in the Applied Steps pane to see what your data looked like at that point. This doesn’t delete anything – it just shows you the state of your data at that step. You can then decide whether you want to delete the later steps or modify them.
Important Warnings and Limitations
Before you start deleting steps in Power Query, here are some critical things you need to know:
No Recovery Option
Unlike Excel’s Ctrl+Z, once you delete a step in Power Query, you cannot get it back. There’s no undo for the undo. Always double-check before deleting.
Step Dependencies
Power Query will warn you if deleting a step might break your query. This happens when later steps depend on transformations made in earlier steps. For example:
- If you delete a step that removed a column, but a later step tries to use that column
- If you delete a step that changed data types, but subsequent steps expect those specific data types
Source Steps Cannot Be Deleted
You cannot delete the “Source” step (usually the first step) as it defines where your data comes from.
Immediate Effect
When you delete a step, the change takes effect immediately in the preview. However, the full refresh happens when you close and apply the query.
Performance Impact
Deleting early steps forces Power Query to recalculate all remaining steps, which can be slow with large datasets.
Query Dependencies
If other queries reference this query, deleting steps here might break those dependent queries.
Best Practices for Safe Undoing
- Test Before Committing: Before making major changes, consider duplicating your query so you have a backup version.
- Work from Bottom Up: When deleting multiple steps, it’s usually safer to delete from the most recent step backward rather than deleting middle steps.
- Check Preview: Always review the data preview after deleting steps to ensure your data still looks correct.
- Save Regularly: Close and apply your changes periodically so you’re not working with too many unsaved modifications.
When Deleting Steps Goes Wrong
If you delete a step and see error messages in subsequent steps, you have a few options:
- Restore the step: Unfortunately, you’ll need to recreate the deleted step manually
- Modify dependent steps: Edit the steps that are now broken to work without the deleted transformation
- Start over: In some cases, it might be easier to start fresh from an earlier point in your query
Power Query’s step-by-step approach makes it relatively easy to undo changes, even without a traditional undo button.
The key is understanding that each step builds on the previous one, so deleting steps can have a cascading effect on everything that follows.
Remember, 99% of the time when you need to “undo” something in Power Query, deleting the problematic step (or steps) from the Applied Steps pane is exactly what you need to do.
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