This is a generic error thrown by iPhone that can happen for a variety of reasons. Most of the time this error can be fixed by changing the internet connection or using VPN.
1. Make sure that your phone is connected to stable internet to be able to download the eSIM. Satellite-based connections such as those found on ships or airplanes often won't work.
2. Make sure that Airplane mode is OFF.
3. If you have too many old eSIMs in your phone, delete some to free up memory.
4. Certain ISPs, corporate networks, and free WiFi networks block download protocols, or specifically eSIM download protocols. You can use VPN to bypass this restriction. Well known examples are:
- Qatar Airport WiFi
- ISPs in some countries (such as Oman) block downloads of non-domestic eSIMs. You can try downloading eSIMs over a VPN connection
- Restrictions imposed by the SM-DP+ servers due to sanctions (e.g, if you are connecting from an IP address belonging to Russia or another widely sanctioned country, most likely you will need to use VPN to be able to download an eSIM)
There are some rare cases when you can see the same error displayed if:
- eSIM is already downloaded to your phone. Please check the Settings->Cellular menu to see if the eSIM is already downloaded.
- You have an eSIM from Claro Brazil on your phone. Claro Brazil eSIMs will block any other eSIM from being downloaded, and the only way to free your eSIM chip is to delete it. Occasionally Verizon eSIM users report the same problem.