I closed bitcoin core
I created an Alix folder but, as I don't have a "wallet" folder, I put an Alix1 folder one in bitcoin and an Alix2 folder in Alix1
I changed the wallet.dta, I put one of mine.

Open bitcoin core
Looked for in "file", "open wallet", and there is the Alix1 folder, marked in gray, as open, but not the folder, it was the wallet before. So last night I opened another wallet2.dat (file), with loadwallet, upgrade didn't work it indicated a lack of passphrase, but I don't normally have one. And that night I launched a rescanblockchain. And I have my wallet.dat. but no upgrade that works.
I'm wondering but does the fact that the file is in Notepad format change anything? (. Dat, but opened with Notepad)