Password must be at least 8 characters when set
Admin Edit user tried to set a password that was non-empty but shorter than 8 characters. API: Password must be at least 8 characters when set.
Why this happens
Leaving the password field blank means “do not change.” Any typed value must meet the minimum length. Distinct from bulk import Password too short (min 8). and from member change-password rules on Account Settings.
Diagnose and fix
1. Enter at least 8 characters, or clear the field to leave the existing password.
2. Save again from Manage users / Edit user.
3. Members resetting via email use the reset form (same 8+ expectation in the UI).