My wife and I needed to exchange MacBooks so one of us could take advantage of a higher OS. Both computers are older and are at their maximum OS. After backing up computer #1 on Mojave we tried to migrate to computer #2 on High Sierra but #2 says it can not restore a backup from a higher OS. What can be done to transfer all the files and documents from #1 to #2?
MacBook Pro 15″, macOS 10.13
If you were using this method If you can't back up or restore your Mac using Time Machine that would explain the error message. The Older computer does not Qualify to run the newer version of Mojave.
The solution would be to setup Time Machine Back on the older computer where you what to documents place - attach the TM Backup Drive - open Time Machine Application and choose the individual files and click Restore.
I did as you said, set up Time Machine on the older computer (#2) and attached the T M Backup drive. I then opened the T M application but it does not reveal any files to restore.
Follow along from a similar issue as the one you are experiencing and possible solution. Posting from @ BDAqua specifically
regressed to an older OS but now my backup won't restore
