HTTP 4xx Client Error Status Codes

curl -i -X POST https://example.com/api -H 'Content-Type: application/json' -d '{bad json}'

# Malformed or invalid request

curl -i https://example.com/private

# Authentication required or invalid

HTTP/1.1 402 Payment Required

# Reserved / rarely used

curl -i -H 'Authorization: Bearer token' https://example.com/admin

# Authenticated but not allowed

curl -i https://example.com/does-not-exist

# Resource does not exist

curl -i -X PATCH https://example.com/static-page

# Method not supported on target resource

curl -i -H 'Accept: application/xml' https://example.com/json-only

# No acceptable representation available

curl -x http://proxy.example.com:8080 https://example.com

# Proxy requires authentication

HTTP/1.1 408 Request Timeout

# Server timed out waiting for request

curl -i -X PUT https://example.com/api/items/1 -H 'If-Match: "stale-etag"' -d '{"x":1}'

# Request conflicts with current state

curl -i https://example.com/removed

# Resource intentionally removed

curl -i -X POST https://example.com/upload --data-binary @file.bin

# Missing required Content-Length

curl -i -X PUT https://example.com/item/1 -H 'If-Match: "wrong"' -d '{"a":1}'

# Conditional request condition not met

curl -i -X POST https://example.com/upload --data-binary @huge.tar

# Payload too large

curl -i 'https://example.com/search?q=very-long-string'

# Request target too long

curl -i -X POST https://example.com/api -H 'Content-Type: text/plain' -d 'name=ada'

# Request body media type not supported

curl -i -H 'Range: bytes=99999999-999999999' https://example.com/file.zip

# Requested byte range is invalid

curl -i -H 'Expect: some-unknown-expectation' https://example.com

# Expectation cannot be met

HTTP/1.1 418 I'm a teapot

# Humorous / non-standard in practice

curl -i https://example.com

# Request sent to wrong origin/server

curl -i -X POST https://example.com/api/users -H 'Content-Type: application/json' -d '{"email":"not-an-email"}'

# Semantically invalid content

LOCK /webdav/file.txt HTTP/1.1

# Resource is locked

PROPPATCH /webdav/resource HTTP/1.1

# Dependent action failed

HTTP/1.1 425 Too Early

# Replay-risk request rejected

HTTP/1.1 426 Upgrade Required
Upgrade: h2c

# Client must switch protocol

HTTP/1.1 428 Precondition Required

# Conditional request required

curl -i https://api.example.com/v1/search

# Rate limit exceeded

curl -i -H 'Cookie: huge=...' https://example.com

# Headers are too large

HTTP/1.1 451 Unavailable For Legal Reasons

# Blocked for legal reasons