iOS shows this when it cannot complete a change to your cellular lines. It is usually a transient failure rather than a problem with the plan itself.

## What to try

1. **Restart your phone**, then try again.
2. **Check your internet connection**, and switch Wi-Fi networks if you can.
3. **Turn off any VPN.**
4. **Try again in a few minutes.** This error often clears on its own.
5. **Check whether the change actually applied.** Open Settings, then Cellular. Sometimes the change worked and only the confirmation failed.
6. **Update iOS**, then restart.

## If you were switching your data line

Do it from Settings, then Cellular, then Cellular Data, and choose the line. Changing several things at once is more likely to fail than one change at a time.

## If you were installing

Then the failure is in installation rather than a plan change. See ["Cellular plan cannot be added"](https://simfuse.app/help/articles/troubleshooting-cannot-be-added).

## If it keeps happening

Contact us with your iPhone model, your iOS version, and what you were trying to change. Include your ICCID so we can check the line's state from our side.