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BaseCamp™ No Longer Opens after Catalina 10.15 Mac Update

The latest version of BaseCamp™ software for Mac 4.8.7 is compatible with 10.15 Catalina Mac operating system update. With the release of the Catalina operating system update, all 32 bit application support has been removed. If your Mac computer is no longer opening BaseCamp™, you may have an older version of application that was not updated to 64 bit. Try uninstalling BaseCamp™ and installing the latest version 4.8.7 again.

Uninstalling Garmin BaseCamp™

How to Install Garmin BaseCamp™