If you see the iCloud error 18003 when you are using iTunes on your Mac computer/laptop, resolve it by performing the step-by-step instructions given here.
More Information Button
If you see the More Information button, click it and perform the instructions show on the screen.
MacOS Mojave Or Later
- Step 1: On the home screen of your Mac computer, navigate to the Apple menu and select the System Preferences option.
- Step 2: Click the Software Update button.
- Step 3: If an update is available for your Mac, you will see the Update Now button. Click it to update the Mac computer to the most recent version.
- Step 4: Select the ‘Automatically keep my Mac up to date’ option.
- Step 5: macOS High Sierra, Sierra, EI Capitan, or earlier
- Step 6: First, launch the App Store application on your Mac computer.
- Step 7: Click the Updates tab at the top of the screen and select the Update All option.
- Step 8: If this option is not visible, the system is up to date.
- Step 9: To download updates automatically, go to the Apple menu and select System Preferences -> App Store -> Download newly available updates in the background to fix iCloud error 18003.
- Step 1: Launch iTunes, navigate to menu, and select the Help option followed by the Check for Updates option.
- Step 2: Carry out the on-screen prompts to install the most recent version of iTunes.
Disable The Security Software
- Step 1: The antivirus, firewall, or malware blocker software installed on your computer might interfere and causes the problem.
- Step 2: Disable the security software temporarily.
- Step 3: You can also customize the settings.
- Step 4: If the iCloud error 18003 still persists, remove the security software from the Mac computer.
- Step 1: Restart the Mac computer.
- Step 2: If the problem occurs when you connect your iPhone to the computer, you have to restart the iPhone as well.