How does try_files work?

try_files is the standard way to serve a file if present and otherwise route to an application or a fallback. It is common for single-page apps, where unknown paths must return index.html.

location / {
    root /var/www/app;
    try_files $uri $uri/ /index.html;
}

location /api/ {
    try_files $uri @app;
}

location @app {
    proxy_pass http://backend;
}

Fallback forms

• A URI such as /index.html triggers an internal redirect and location matching runs again
• A named location such as @app forwards to an internal handler
• An equals code such as =404 returns that status directly
• The final fallback must exist or be a valid status or named location

Because the fallback URI is re-matched, a broad SPA fallback can accidentally swallow API or asset 404s. Put API and asset locations before the catch-all, or use more specific fallbacks.