Migrate Debian GNU/Linux 9 (stretch) 64-bit to Mint ??
 

Can one migrate to another flavor without wiping out the drive?
Thanks!

Mint is Ubuntu-based. Ubuntu is Debian-based. Thus, at least in theory, it should be feasible at least for an experienced user. Better not to try if not well experienced, or on a production system, and certainly don't try on a system that hasn't had all important files adequately backed up. Also, the Mint version would matter. One should not expect success jumping the gap from a several years old Stretch to Mint's latest, 20. The same base version should be upgraded to have a decent chance at success. Finally, anyone who has to ask the OP question unlikely has the experience required to expect success.

OTOH, if the Stretch system has /home on a separate filesystem, the answer is a vastly different, as /home can be reused, while the / filesystem can be wiped to install Mint afresh. The new mint should have little problem migrating existing user settings where necessary from Stretch's to newer versions.

It's not something I would try, unless I had a machine or VM simply for experimentation.

If you choose to try it, back everything important up to external media before doing so.

Feasible? I strongly disagree. It might be possible, as an experiment, for a very experienced user. Certainly one that wouldn't have to ask this question.

That sounds more realistic.

Thanks!
Been a long time since playing with systems.
Gunna do a clean install that way theirs no guessing :) This is my internet machine so email/bookmarks the only vital information.