Thanks for helping me out.
I deleted the data directory on the new computer and copied the data director on the old computer to the new computer.
When I open Mnemosyne on the new computer, I get a series of error messages.
1) Could not create default ...dba media
2) Previous drive letter no longer available
3) If you are using a USB key, refer to the instructions on the website so as not to be affected by drive letter changes
4) It then tries to open the Mnemosyne database from the Program Files (x86) Mnemosyne folder
5) If I cancel, there is an unexpected error message
6) Failed to execute script mnemosyne message
I am attaching the screen shots. The file is called "Series of Error Messages"
If I try to open at step 5 the most recent back-up from this folder on the new computer
I also get error messages.
The file with screen shots is called "Cannot load a backup" . I get another series of messages
5) When I try to open the Mnemosyne databases, I go the AppData\Roaming\Mnemosyne\ folder
6) I select and open the most recent backup
7) Mnemosyne asks if I want to replace the current database with one restored from this backup?
6) I get the unexpected error message
7) Failed to execute script mnemosyne message