remix-run/remix · error · Error

invalid bypass pattern ${JSON.stringify(pattern)}: empty wil

Error message

invalid bypass pattern ${JSON.stringify(pattern)}: empty wildcards are not allowed

What it means

parseBypassSegment throws when a wildcard segment is exactly '{}', i.e. an unnamed wildcard. Wildcards must have a name like {id} for the pattern to be meaningful and for downstream matching. An empty '{}' is treated as a malformed pattern.

Source

Thrown at packages/cop-middleware/src/lib/cop.ts:282

function parseBypassSegment(
  pattern: string,
  segment: string,
  isLastSegment: boolean,
): BypassSegment {
  if (segment === '') {
    throw new Error(
      `invalid bypass pattern ${JSON.stringify(pattern)}: empty path segments are not allowed`,
    )
  }

  if (!segment.startsWith('{') || !segment.endsWith('}')) {
    return { type: 'static', value: segment }
  }

  let wildcardName = segment.slice(1, segment.length - 1)
  if (wildcardName === '') {
    throw new Error(
      `invalid bypass pattern ${JSON.stringify(pattern)}: empty wildcards are not allowed`,
    )
  }

  if (wildcardName === '$') {
    throw new Error(
      `invalid bypass pattern ${JSON.stringify(pattern)}: "{$}" is not supported in cop-middleware`,
    )
  }

  if (wildcardName.endsWith('...')) {
    if (!isLastSegment) {
      throw new Error(
        `invalid bypass pattern ${JSON.stringify(pattern)}: tail wildcards must be last`,
      )
    }

    if (wildcardName.length === 3) {

View on GitHub (pinned to 9696913134)

Solutions

1. Give the wildcard a name: '/users/{id}' instead of '/users/{}'
2. If any single segment should match, still name it, e.g. '/files/{name}'

Example fix

// before
cop.addInsecureBypassPattern('/users/{}')
// after
cop.addInsecureBypassPattern('/users/{id}')

const segments = path.split('/')
if (segments.some((s) => s === '{}')) throw new Error('empty wildcard in pattern')

function isValidWildcardSegment(segment: string): boolean {
  return !(segment.startsWith('{') && segment.endsWith('}') && segment.length === 2)
}

When it happens

Trigger: addInsecureBypassPattern('/users/{}') or any pattern containing a '{}' segment.

Common situations: Placeholder templates left unfilled; regex-based generation of patterns producing '{}' when the capture name is missing; typos deleting the wildcard name.

Related errors

• invalid bypass pattern ${JSON.stringify(pattern)}: tail wild
• invalid bypass pattern ${JSON.stringify(pattern)}: tail wild
• invalid bypass pattern ${JSON.stringify(pattern)}: path must
• invalid bypass pattern ${JSON.stringify(pattern)}: query str
• invalid bypass pattern ${JSON.stringify(pattern)}: empty pat

AI-assisted analysis of remix-run/remix@9696913134 (2026-08-27). Data as JSON: /api/errors/7082df23c50577eb. Report an issue: GitHub.