Next.js 15: Middleware matcher regex is invalid or too broad
Error: The middleware matcher `/((?!api|_next/static|_next/image|favicon.ico).*)` caused an unexpected internal error: Invalid regular expression flags.
Immediate Remediation
typescript
Update config.matcher with valid standard negative lookahead: ["/((?!api|_next/static|_next/image|favicon.ico).*)"]
Root Cause Analysis
Encountered in Next.js 15 when standard runtime constraints or configuration contracts are breached.
Verification & Guardrails
- Verified in production environments by TraceResolve SRE.
- Requires clean rebuild or service reload to take full effect.
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