There are several reasons why an external hard drive may not be accessible or detected when you connect it to your computer.
While it is possible that your external hard drive may have come with bundled software that may be incompatible with newer operating systems, this is typically just ‘back up’ software, and the drive is not dependent on that software to function.
The external hard drive itself, under normal circumstances, should be detected by your operating system, without the need of drivers, software, or firmware updates.
If your external hard drive is not accessible please try these basic troubleshooting steps first.
Basic hardware troubleshooting steps:
For advanced troubleshooting steps select your operating system:
Check both Device Manager and Disk Management in the Computer Management console:
Once you have located the drive you will want to look for the following:
Does it show RAW or Unallocated? Either of these indicates a possible issue with the drive’s formatting.
If the drive shows as RAW or Unallocated and you have already tried a different port, cable, and computer but you need the data, then you will want to consider data recovery.
If you do not need any data from the drive, you should be able to reformat the drive to restore accessibility. Read our How To Format Your Drive article for instructions on the process. WARNING: Formatting erases all data on the drive.
If the drive is formatted correctly for Windows you should see the following information:
Drive not detected troubleshooting:
If the drive was not detected under Disk Drives then check the following:
If you see Code 10 and have already tried another cable and computer then the drive has probably failed.
If you need the data on the drive, then you will want to consider data recovery.
If you do not need the data and the drive is still within warranty, you will want to have the drive replaced. Visit the Warranty and Replacements section on Seagate.com for further details.
If you see Code 28 (this may work for others codes too, ie Code 43) then try the following:
Warning: This can be dangerous to your data and you should disconnect your external drive before attempting this.
If the drive is not showing on your desktop or within Finder check Disk Utility.
Open Finder > Applications > Utilities > Disk Utility
If the drive is not detected in Disk Utility then see the System Information/System Profiler section.
If you are using macOS 10.13 or higher then click view in the upper left and select “Show All Devices” which allows you to see both the disk as well as volumes.
The non-indented entry is the physical disk entry and when selected should say media in the name. In Mac OS X version 10.6 to 10.10 this entry will display the capacity of the drive instead of saying media. The indented entries will vary depending on how the drive is formatted but these entries will be volumes or containers associated to the physical disk.
Select the indented entry for your drive and click on the “Mount” button at the top of the Disk Utility. If the drive didn’t mount this indicates some level of file system corruption.
Select the indented entry and then click on First Aid
If the drive is not detected in Disk Utility then check System Information/System Profiler.
Hold the Option key then click on the Apple Icon, the first entry should say System Information/System Profiler. If it says About this Mac then press and hold the option key again.
Once in System Information/System Profiler:
If the drive is not in System Information/System Profiler or in Disk Utility then try another Mac to see if the drive is detected there. If the drive is detected on the other Mac then continue with the following Apple specific troubleshooting.
Trying some of Apple specific troubleshooting may help resolve the issue.
Reboot into Safe Mode and see if the drive is detected. If it is detected then reboot back into normal mode and see if the drive is now detected
Apple Safe Mode - https://support.apple.com/en-us/HT201262
If that does not resolve the issue then try each of the following resets. Sometimes it helps to do these more than once.
Apple NVRAM reset - https://support.apple.com/en-us/HT204063
Apple SMC reset - https://support.apple.com/en-us/HT201295
If you have exhausted either of the Windows or Macintosh advanced troubleshooting steps, and your external hard drive is still not accessible or detected, for further assistance contact Seagate support.