HTTP
406 Not Acceptable
The server cannot produce a response matching the Accept headers sent by the client.
When You See This Code
When requesting a content type the server doesn't support (e.g., Accept: application/xml when only JSON is available).
How to Fix
Adjust the Accept header to a format the server supports.
Specification
View RFC / Specification →Guides
Understanding HTTP Status Codes: A Complete Guide
HTTP Fundamentals
HTTP Redirects: 301 vs 302 vs 307 vs 308
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HTTP Caching: Cache-Control, ETags, and 304 Responses
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Choosing the Right HTTP Status Codes for REST APIs
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gRPC Status Codes: A Practical Guide
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Debugging 502 Bad Gateway Errors
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Debugging CORS Errors: A Developer's Guide
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Debugging Timeout Errors: 408 and 504
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401 Unauthorized vs 403 Forbidden: When to Use Each
Security & Authentication
Essential HTTP Security Headers
Security & Authentication
Complete Guide to HTTP Methods: GET, POST, PUT, PATCH, DELETE
HTTP Fundamentals
Essential HTTP Headers Every Developer Should Know
HTTP Fundamentals
HTTP/2 vs HTTP/3: What Changed and Why
HTTP Fundamentals
How to Implement and Handle Rate Limiting (429)
API Design
API Versioning Strategies: URL, Header, and Query Param
API Design
Designing Consistent API Error Responses
API Design
Debugging 503 Service Unavailable Errors in Production
Debugging & Troubleshooting
TLS/SSL Certificate Troubleshooting Guide
Debugging & Troubleshooting
OAuth 2.0 Flows Explained: Authorization Code, Client Credentials, PKCE
Security & Authentication
JSON Web Tokens: Structure, Signing, and Common Pitfalls
Security & Authentication
API Keys vs OAuth vs JWT: Choosing the Right Auth Method
Security & Authentication