When trying to download an operating system using the Installation Assistant, the following notification appears:
Unable to download the operating system installation files.
- Check your Internet connection. If you are using Wi-Fi or mobile network, connect the computer to the Internet using Ethernet cable to ensure network stability.
- Do not close the lid of your portable Mac when downloading.
- Click OK on the error message and click Resume.
- Try downloading the operating system again.
Try accessing this page. If the page is accessible, follow the steps below. If you cannot access it, try later.
Open Terminal.app (Finder → Applications → Utilities) and execute the command:
- Make sure that the address is resolved and you receive response from the server.
Press Control + C combination on the keyboard to stop the process and see the results.
- If you cannot connect to
download.parallels.comcheck DNS settings and make sure that port 443 is opened for TCP protocol (Firewall settings).