nginx: [emerg] unknown directive 'xyz'

The error “nginx: [emerg] unknown directive ‘xyz’” means Nginx encountered a configuration directive it does not recognize. The parser stops immediately and Nginx fails to start.

What It Means

Nginx parses its configuration files (typically in /etc/nginx/) sequentially. When it reads a line that starts with a word it does not recognize as a valid directive, it raises an unknown directive error and exits. This is a fatal configuration error — Nginx will not start until it is fixed.

Why It Happens

• There is a typo in a directive name (e.g., servername instead of server_name).
• A directive is missing its terminating semicolon, causing the next line to be parsed as part of the directive name.
• A required Nginx module is not compiled or loaded (e.g., proxy_pass requires ngx_http_proxy_module).
• A dynamic module was not loaded with load_module in the main context.
• The directive is placed in the wrong context (e.g., server_name inside http block instead of server block).

How to Fix It

1. Find the exact line with the error

sudo nginx -t

Nginx reports the file path, line number, and the unknown directive.

2. Check for missing semicolons

Each directive line must end with ;:

server_name example.com;  # correct
server_name example.com   # missing ; → error on next line

3. Verify the directive spelling

# Correct
server_name example.com;
root /var/www/html;
proxy_pass http://backend;

# Incorrect
servername example.com;
rote /var/www/html;
proxy_pass: http://backend;

4. Install the missing module

sudo apt install nginx-extras  # includes many additional modules

5. Load a dynamic module

load_module /usr/lib/nginx/modules/ngx_http_geoip_module.so;

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