How to fix PGRST101: Missing Content-Type header in Supabase

Inspect the HTTP exchange with curl, a browser devtool, or a network proxy. The request must include the Content-Type that matches the payload.

curl -v -X POST https://your-project.supabase.co/rest/v1/widgets   -H "apikey: YOUR_ANON_KEY"   -H "Authorization: Bearer YOUR_JWT"   -H "Content-Type: application/json"   -d '{"name":"test"}'

If the Content-Type line is absent, PostgREST raises PGRST101. Re-run curl with the header and you should get a 201/200 response instead of 405.

When you call Supabase via fetch, axios, or another HTTP client, always add the header before calling JSON.stringify on the payload.

const response = await fetch('https://your-project.supabase.co/rest/v1/widgets', {
  method: 'POST',
  headers: {
    apikey: process.env.SUPABASE_ANON_KEY,
    Authorization: `Bearer ${token}`,
    'Content-Type': 'application/json', // required
  },
  body: JSON.stringify({ name: 'test' }),
});

If you build headers by merging objects, make sure you don’t accidentally remove Content-Type. Supabase?s JS client already does this for you when you call .insert(), but custom fetch wrappers still need the header.

Browsers set the Content-Type (with the boundary) automatically when you pass a FormData instance. Do not manually override it with a string such as 'multipart/form-data', because that strips the boundary and can trigger the same error. Instead, only append Content-Type when you control the media type:

const form = new FormData();
form.append('file', fileInput.files[0]);

await fetch('https://your-project.supabase.co/rest/v1/uploads', {
  method: 'POST',
  headers: {
    apikey: SUPABASE_KEY,
    Authorization: `Bearer ${token}`,
    // DO NOT set Content-Type here when using FormData
  },
  body: form,
});

If you need to send JSON, make sure you call JSON.stringify and set Content-Type: application/json explicitly.

If you front Supabase with Cloudflare, Vercel, or your own API gateway, confirm those services do not drop the Content-Type header. Inspect the raw request reaching Supabase or add temporary logging to the middleware:

addEventListener('fetch', (event) => {
  console.log('incoming headers', Object.fromEntries(event.request.headers));
  return event.respondWith(fetch(event.request));
});

If the header disappears before Supabase sees it, configure the edge layer to pass through all headers or rebuild the request and re-add Content-Type before forwarding.

The official Supabase libraries set the required Content-Type automatically when you use the table helpers or service functions. Replace raw fetch calls with:

await supabase.from('widgets').insert({ name: 'test' });

If you still need custom fetch logic (for example, fetching signed URLs or invoking edge functions), copy the headers that the Supabase client sends by default so that PostgREST receives the same metadata.