In this article, I will explain how to fix the could not build optimal proxy_headers_hash error on Nginx when doing a configuration test with nginx -t.
This warning is displayed when publishing several dozen virtualhosts on Nginx in reverse proxy.
To solve this problem, you need to increase the value of the following parameters:
Open file /etc/nginx/nginx.conf :
sudo nano /etc/nginx/nginx.conf
In the block http { ... } add or modify the values of the parameters below:
proxy_headers_hash_max_size 1024;
proxy_headers_hash_bucket_size 128;
Save changes.
Test the configuration again with the command sudo nginx -t, the warning message should no longer be present.
Reload the configuration to take into account:
sudo systemctl reload nginx
