In addition to this general debugging advice, I would first check whether the error message really does not apply.

If MySQL claims that the user koha_library is using an invalid password for the connection, then maybe the password is the wrong MySQL password for this user?

This is something only the OP can check (and double-check).

In reply to Re^2: DBI Connection failed by Corion
in thread DBI Connection failed by Anonymous Monk

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