could not build the server_names_hash, you should increase server_names_hash_bucket_size Nginx / Apache Origin: Edge & web server OSI layer 7 · Application Last updated 5 Nov 2026

Nginx: nginx: [emerg] could not build the server_names_hash, you should increase server_names_hash_bucket_size: 64

A very long server_name (or many names) doesn't fit the hash bucket.

Exact message you may see could not build the server_names_hash, you should increase server_names_hash_bucket_size: 64nginx: [emerg] could not build the server_names_hashincrease server_names_hash_bucket_sizecould not build the variables_hash, you should increase either variables_hash_max_size
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Seen on: Nginx Linux

Meaning

Add server_names_hash_bucket_size 128; (or 64/256) to the http {} block; raise server_names_hash_max_size if you have thousands of names. Typical with long domain names or many virtual hosts on one server.

Common causes

  • Very long domain/server_name
  • Hundreds of server names
  • Default bucket size 32/64 too small
  • Wildcard/regex names
  • Generated vhosts

⚡ Quick fix

  1. In http {}: server_names_hash_bucket_size 128;
  2. Increase server_names_hash_max_size for many names
  3. Reload after nginx -t

Detailed fix by platform

Nginx

  1. http { server_names_hash_bucket_size 128; }

How to diagnose

  1. Names — Long/many?
  2. Bucket — Current value?
  3. Fix — Increase in http?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Edge & web server. Errors that are often confused with or caused by this one (click to open):

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