Apple’s rollout of iOS 26 has triggered a wave of activation failures for iMessage, particularly affecting users who rely on their phone number rather than an email address. The issue stems from how iOS 26 handles SIM configurations, especially in cases where an inactive SIM—physical or eSIM—is still linked to the same phone number as the active one. When this duplication occurs, iMessage fails to verify the number correctly, resulting in messages being sent as SMS or RCS (green bubbles), or defaulting to an email address. Apple has confirmed the bug and published a fix that doesn’t require a software update. Users should open Settings > Cellular and check for multiple SIMs tied to the same number. If an inactive SIM is present, it must be removed—either physically or by deleting the eSIM profile. Once cleaned up, users should go to Settings > Messages > Send & Receive, deselect and reselect their phone number, and toggle iMessage off and on to trigger reactivation. This issue is especially common among users who switched carriers, upgraded to eSIM, or restored backups from older devices. Apple’s support documentation also notes that skipping eSIM activation during initial setup can cause iMessage to fail silently. While the fix is manual, it’s effective, and Apple has not indicated that a patch is coming. The situation has reignited criticism of Apple’s reliance on phone number verification for iMessage, especially as the company pushes deeper into eSIM territory. For now, users experiencing persistent issues are advised to remove any legacy SIM configurations and reinitiate the activation flow manually.