Error Code -8003

Dear helpful person,

I have been trying to transfer files onto an external hard drive from my mac and another external hard drive. I get this error message "The operation can't be completed because an unexpected error occurred (Error code -8003). This hard drive had always worked and only recently shown this error, I have cross checked it with the hard drive tech support and it appears to be an error code from the mac. I have backed up all of the files on another drive and re-formatted and it hasn't been fixed. There are no files appearing in my trash which seems to have been the topic of other threads showing the same error code. I have gone into disk utilities and clicked repair, but that hasn't helped either, I get the message "Updating boot support partitions for the volume as required." but then nothing happens and it's not repaired. Please advise on how I can fix this problem as I cannot find this problem in this context on another thread.

Kind Regards

Jordan