Manual:$wgPasswordPolicy

Details
A password policy is of the form


 * etc. are user groups, plus the special group which is required to be present and applies to everyone.


 * etc. are arbitrary check names, defined in the subarray.


 * etc. are policy values, passed to the appropriate callback defined in the subarray.  If the same check applies to a user via multiple groups, it will be applied with the  of the values.
 * Alternatively, could be an array with the fields  (same as above),  (when set to true, users will be shown a password change form during login if the check fails) and  (like  but the form cannot be skipped).

Removed in MW 1.35+, use  instead. Deprecated in MW 1.35+, use  instead.
 * etc. are [ https://php.net/language.types.callable PHP callables], which receive three arguments: the defined value, the  object and the password, and return a StatusValue. A fatal status means the password can't be used, even for login; a non-fatal error means the value is not accepted as a new password (on account creation or password change), but can be used for login; the user will be shown a (skippable) password change form.
 * Default checks (found in ):
 * &mdash; Minimum length a user can set
 * &mdash; Passwords shorter than this will not be allowed to login, regardless if it is correct.
 * &mdash; Maximum length password a user is allowed to attempt. Prevents DoS attacks with pbkdf2.
 * &mdash; Password cannot match username
 * &mdash; Your password must not appear within your username.
 * &mdash; Blacklists some passwords which have been used by MediaWiki unit tests in the past.
 * &mdash; Blacklist passwords which are known to be commonly chosen. Set to integer n to ban the top n passwords.  If you want to ban all common passwords on file, use the  constant.  See also  (the default file comes with MediaWiki and has 10K passwords).
 * &mdash; Same as the previous one, except uses the larger blacklist that comes with the wikimedia/password-blacklist library.
 * &mdash; Password not in best practices list of 100,000 commonly used passwords.

Examples
This example shows how to change selected policies for all users:

This example shows how to change selected policies for users of the "sysop" group:

Disabling all password policies
For development machines, it might be helpful to disable all password policies, which can be done with the following line: