WhatsApp is implementing server-side restrictions that will prevent users from logging in if their devices run outdated versions of Android or iOS. The rollout is happening gradually across Meta's servers, regardless of which version of the WhatsApp app is installed on the device.
When affected, users will see a message stating "Update your phone's software to sign in again," prompting them to install the latest OS version through their device settings. The exact versions of Android and iOS that trigger the block have not yet been disclosed, though the restriction is being distributed incrementally rather than enforced all at once.
This move aligns with WhatsApp's ongoing effort to ensure users maintain current software, which typically includes important security patches and compatibility improvements. The server-side enforcement means users cannot work around the restriction by simply updating the app alone—a full operating system update will be required.