Using external SSD as startup disk issue
Hello, I recently purchased a SanDisk extreme and I am trying to use it as a startup disk for more storage. I have been restarting my computer and holding Command + R and hitting the disk utility. I have tried to restart from the SSD, however, it always comes back saying: security settings do not allow this Mac to use an external start-up disk. I have gone into the startup security utility, but it keeps saying no Administrator was found, even though I just signed into the administrative account. Thanks.
Johnny’s iMac 27" 5K, iMac 27″