This appears after the profile has downloaded, when iOS tries to bring the line up. The plan is on your phone; it is the activation step that has failed.
Try these in order
- Wait and retry. Open Settings, then Cellular, choose the SimFuse line and turn it on again. Activation can fail once and succeed immediately after.
- Restart your phone. The most effective single step here.
- Check your internet connection. Activation needs one. Wi-Fi is fine.
- Turn off any VPN and try again.
- Toggle airplane mode on, wait ten seconds, off.
- Update iOS, then restart and retry. Activation bugs in specific iOS versions are real.
- Check the plan has not expired. A plan that ran out of validity before you activated it will not come up. See "How validity periods are counted".
Do not delete the eSIM to fix this
Deleting is permanent and does not return your activation code. It turns a recoverable problem into one that needs a reissue. See "Deleting an eSIM, and when not to".
If it still will not activate
Contact us with your ICCID, your iPhone model, your iOS version, and when you first tried. We can see from our side whether the line is provisioned and waiting, which tells us whether this is your phone or us.