The “Unable to Complete Cellular Plan Change” error typically indicates a hiccup in the eSIM installation process, which can stem from various issues:

1. Exceeding the eSIM Limit: Modern eSIM-capable devices support the installation of multiple eSIMs. However, the maximum number of eSIMs you can store simultaneously varies by device model. For instance, iPhones may accommodate between 5 to 10 eSIMs, contingent on the device’s storage capacity. For detailed information regarding your device’s eSIM capacity, it’s recommended to consult with the device’s manufacturer.

   If your device has reached its eSIM storage limit, consider deleting any unused eSIM profiles. Guidance on removing eSIMs can be found under: How to Delete an eSIM from Your Device.

2. Cellular Data Turned Off: Ensure that cellular/mobile data is activated in your device’s settings to proceed with the eSIM installation.

3. Duplicate eSIM Installation Attempt: Most eSIMs are designed for a single installation. Attempting to reinstall an already activated eSIM can cause this error.

   To check if the eSIM is already installed, navigate to Settings > General > About and scroll to locate the ICCID (a 20-digit number beginning with 89 and ending with an additional digit). If the ICCID corresponds to the eSIM in question, consulting the eSIM installation guide for troubleshooting steps may resolve connectivity issues.

4. Weak Installation Connection: Attempting to install an eSIM over unreliable networks, such as ship or public Wi-Fi, can lead to installation failures.

Addressing these common culprits can often resolve the issue, enabling successful eSIM activation and use. For further assistance, refer to the eSIM installation instructions provided or reach out for support.