This is sort of a snafu.
Apple appears to have pulled the latest macOS Mojave Security Update (2020-005) from its download choices. The update was released on September 24 alongside the macOS Catalina 10.15.7 update. The company has also removed the Safari 14 for macOS Mojave from its available downloads.
Per Mr. Macintosh, the updates were causing numerous problems for users still running macOS Mojave.
macOS Mojave users who installed the updates have been noticing memory issues, slow boot times and Finder stalling, numerous system.log entries, and crashes when attempting to use Migration Assistant, among other problems. Complaints about the update started shortly after it was released, but Apple did not pull the updates until yesterday.
If you’ve downloaded the updates and are experiencing errors, you can revert to a Time Machine backup, reinstall macOS Mojave, or install macOS Catalina with the current updates to resolve these issues.
Please let us know about your experience in the comments, and we’ll have additional details as they become available.
Via MacRumors and Mr. Macintosh