Laravel preg_match(): No ending delimiter '/' found
Since your regex has a pipe in it, you have to use an array:
public static $rules_save = [ 'class_subjects' => ['required', 'regex:/[0-9]([0-9]|-(?!-))+/'],];From the docs:
When using the
regexpattern, it may be necessary to specify rules in an array instead of using pipe delimiters, especially if the regular expression contains a pipe character.