What is a common reason for an iPhone to refuse installation of a new iOS update?

Insufficient storage space is a common reason for an iPhone to refuse installation of a new iOS update because updates often require a significant amount of free space to download and install. When an iPhone runs low on storage, it may not have enough room to accommodate the temporary files and new system files necessary for the update process. This limitation prevents the installation from proceeding, and the device may prompt the user to free up space before attempting the update again.

While network connectivity issues, outdated hardware models, and app incompatibilities can also affect the update process, insufficient storage is specifically tied to the capability of the device to handle new data, making it a primary concern during updates.