Semantic-Org/Semantic-UI · warning

{name} must be a valid url

Error message

{name} must be a valid url

What it means

Default user-facing validation prompt for the Semantic UI Form `url` rule (settings.rules.url, form.js:1352). It is NOT a thrown exception — it is the message rendered into the `.prompt.label` next to a field when `module.validate.rule` returns false and no custom `rule.prompt` was supplied (resolved at form.js:442 via `settings.prompt['url']`). The check tests the value against `settings.regExp.url`, which requires an `http(s)://` scheme or a `www.` prefix plus a TLD of at least two characters (form.js:1245).

Source

Thrown at src/definitions/behaviors/form.js:1257

    decimal : /^\d+\.?\d*$/,
    email   : /^[a-z0-9!#$%&'*+\/=?^_`{|}~.-]+@[a-z0-9]([a-z0-9-]*[a-z0-9])?(\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)*$/i,
    escape  : /[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g,
    flags   : /^\/(.*)\/(.*)?/,
    integer : /^\-?\d+$/,
    number  : /^\-?\d*(\.\d+)?$/,
    url     : /(https?:\/\/(?:www\.|(?!www))[^\s\.]+\.[^\s]{2,}|www\.[^\s]+\.[^\s]{2,})/i
  },

  text: {
    unspecifiedRule  : 'Please enter a valid value',
    unspecifiedField : 'This field'
  },

  prompt: {
    empty                : '{name} must have a value',
    checked              : '{name} must be checked',
    email                : '{name} must be a valid e-mail',
    url                  : '{name} must be a valid url',
    regExp               : '{name} is not formatted correctly',
    integer              : '{name} must be an integer',
    decimal              : '{name} must be a decimal number',
    number               : '{name} must be set to a number',
    is                   : '{name} must be "{ruleValue}"',
    isExactly            : '{name} must be exactly "{ruleValue}"',
    not                  : '{name} cannot be set to "{ruleValue}"',
    notExactly           : '{name} cannot be set to exactly "{ruleValue}"',
    contain              : '{name} must contain "{ruleValue}"',
    containExactly       : '{name} must contain exactly "{ruleValue}"',
    doesntContain        : '{name} cannot contain  "{ruleValue}"',
    doesntContainExactly : '{name} cannot contain exactly "{ruleValue}"',
    minLength            : '{name} must be at least {ruleValue} characters',
    length               : '{name} must be at least {ruleValue} characters',
    exactLength          : '{name} must be exactly {ruleValue} characters',
    maxLength            : '{name} cannot be longer than {ruleValue} characters',
    match                : '{name} must match {ruleValue} field',
    different            : '{name} must have a different value than {ruleValue} field',

View on GitHub (pinned to 597843ab84)

Solutions

1. Enter a fully-qualified URL matching the regex, e.g. `https://example.com` or `www.example.com`.
2. If you must accept local/custom hosts, switch the rule to a custom regex: `{type:'regExp[/^(https?:\/\/)?[\w.-]+(:\d+)?(\/.*)?$/]'}`.
3. Globally relax the pattern before init: `$.fn.form.settings.regExp.url = /your-pattern/i;`.
4. Override only the message per-field with `rules:[{type:'url', prompt:'Enter a valid website address'}]`.

Example fix

// before
$('.ui.form').form({ fields: { site: { rules: [{ type: 'url' }] } } });
// user types 'localhost'  ->  'Website must be a valid url'

// after: accept scheme-less / local hosts via custom regex
$('.ui.form').form({
  fields: {
    site: {
      rules: [{ type: 'regExp[/^(https?:\/\/)?([\w-]+\.)+[\w]{2,}([:\d]+)?(\/.*)?$/]', prompt: 'Enter a valid website address' }]
    }
  }
});

// Run before .form('validate') / submit
function looksLikeUrl(v) {
  if (!v) return false;
  return /^(https?:\/\/)?([\w-]+\.)+[\w]{2,}([:\d]+)?(\/.*)?$/i.test(v) || /^https?:\/\/localhost([:\d]*)?/i.test(v);
}
if (!looksLikeUrl($field.val())) { /* warn user / block submit */ }

When it happens

Trigger: A field configured with `{identifier:'website', rules:[{type:'url'}]}` whose entered value has no protocol/TLD: `localhost`, `example`, `ftp://files.example.org`, `mailto:a@b.com`, or `intranet-host` (no dot). Any value failing `regExp.url.test(value)` causes `module.get.prompt` to return this string.

Common situations: Localhost / intranet / LAN URLs during dev, deep links without a scheme, custom protocol URLs, or values pasted without `https://`. Also triggered when `{ruleValue}`/`{name}` placeholders are misconfigured, but for this rule there are none.

Related errors

• {name} is not formatted correctly
• {name} must be an integer
• {name} must be a decimal number
• {name} must be set to a number
• {name} must be "{ruleValue}"

AI-assisted analysis of Semantic-Org/Semantic-UI@597843ab84 (2026-08-13). Data as JSON: /api/errors/4eda58fc2156bdf0. Report an issue: GitHub.