2017 MacBook pro 4-usb-c
can not update to Catalina. it states after download (null)
Did you follow: How to upgrade to macOS Catalina.
Before You Upgrade macOS
- Fix any problems before upgrading.
- Run First Aid in Disk Utility while booted from your Recovery HD.
- Backup. Make a bootable clone using CarbonCopy Cloner or use TimeMachine.
- Be sure your startup disk has 18-20GB of free space during the installation.
- Upgrade third-party software for compatibility. See App Compatibility Table - RoaringApps. If you have mission critical software, then DO NOT upgrade until you know that software is compatible with the version of macOS you are about to install.
- Disconnect all third-party peripherals.
- Download the installer which will be in the Applications folder. Quit the installer after it opens, then make a copy of the installer and save it in the Downloads folder. The one in the Applications folder will be deleted after a successful installation.
- The download is large, anywhere between 5 and 9GBs. It takes time to complete. Be patient.
- Double-click on the installer in the Applications folder. Click on the start button to begin the installation.