As for the LaCie hard drive disconnecting from the MacBook Pro issue, the simplest way you can have a shot is to check the cable for tears or wear. Just connect another external drive to your MBP with the same cable to see if it disconnects from the computer device also. If this fix fails to make your LaCie hard drive work well on your MBP, then I guess that some professional solutions are indispensable.
Before diving into the practical solutions, let's figure out the possible factors in the first place:
- The disk was put to sleep.
- There is third-party software blocking the connection.
- The USB or Thunderbolt cable or port is damaged.
- There are software bugs on your Mac.
- The external hard drive or USB drive is corrupted.
- The drive doesn't have a sufficient power supply.
- The drive has an outdated or incompatible disk driver.
For all likely reasons, I will give you professional & practical solutions to fix the trouble that the LaCie external hard drive keeps disconnecting on Mac.
Note that these solutions may cause you data loss, so you have to get all the data on the drive first. The backup is perfect but if you have no one, data recovery software is also wonderful. iBoysoft Data Recovery Software is at your service and you can utilize it to scan for your data!
With data at hand, then you can begin the repair process to fix the LaCie external hard drive disconnecting from your MBP trouble:
- Unplug and replug the drive
- Restart your Mac
- Disable the 'Put hard disks to sleep when possible option
- Switch between a hub or direct connection
- Change the default disk sleep time to maximum
- Disable or uninstall third-party anti-virus programs
- Boot into Safe Mode
- Repair the disk with Disk Utility
- Update or downgrade macOS