Troubleshooting search error 404

When you use the advanced search feature in HTML files exported from Dr.Explain, you may encounter error messages with code 404 instead of search results.

A 404 error means the web server cannot find the page or file the browser is trying to load. This is always a web server configuration issue, not a problem with the backend since the backend is configured not to return error code 404.

Common causes

Typo in URL: check that you're using the correct URL path.
Missing configuration: the web server doesn't have a rule to handle /drexsearch/ requests.

Step 1: Test the backend in browser

Open your documentation in a web browser.
Click on any topic in the menu.
In the browser's address bar, change the URL by removing the filename at the end and adding /drexsearch/ping, for example:

Change from: http://your-server.com/docs/some-file.htm

Change to: http://your-server.com/docs/drexsearch/ping
Press Enter.

What you should see: a message saying "If you see this text, Dr.Explain Search Backend is working..."

If you see this message: the backend is working, but your web server is not configured to forward search requests correctly. Go to Step 3.

If you see this error (or similar):

{"error":"URL \"/drexsearch/ping\" is invalid..."}

This means your web server is adding an extra prefix (/drexsearch in example above) when forwarding to the backend. Go to Step 3.

If you get a different error: the backend might not be running. Go to Step 2 to check if the backend service is running.

Step 2: Test the backend directly

If you have access to the server, connect to it (e.g. via SSH) and open a terminal, then try this command:

curl http://127.0.0.1:8082/ping

What you should see: a message saying "If you see this text, Dr.Explain Search Backend is working..."

If you see this message: the backend is working, but your web server is not configured to forward requests correctly. Go to Step 3.

If you get an error: the backend might not be running. Go to Troubleshooting search error 502 to check if the backend service is running.

Step 3: Check web server configuration

This step requires access to your server's configuration files.

For nginx servers:

Check that your configuration includes this section:

location ~ /drexsearch/(.*)$ {

proxy_pass http://127.0.0.1:8082/$1$is_args$args;

}

For Apache servers:

Check that your configuration includes:

RewriteEngine On

RewriteRule ^(?:.*/)?drexsearch/(.*)$ http://127.0.0.1:8082/$1 [P,L]

Common mistakes to look for:

Typo in the path (e.g., /drxsearch/ instead of /drexsearch/).
Missing the /$1$is_args$args part in nginx or $1 in Apache configuration.
Wrong document root path.

If you find a mistake: correct the configuration and restart your web server. Then test again.

Step 4: Check error logs

This step requires access to your server's log files.

For nginx:

sudo tail -f /var/log/nginx/error.log

For Apache:

sudo tail -f /var/log/apache2/error.log

Look for messages like:

"file not found" — the file doesn't exist at the specified path.
"Primary script unknown" — Apache cannot find the script file.
"upstream not found" — the backend path is misconfigured.