When accessing Neo4j Browser or Bloom, users may encounter a blank screen, with the error ERR_CONTENT_LENGTH_MISMATCH appearing in the web browser’s developer tools.

This error occurs when there is a discrepancy between the expected and actual content length of resources being loaded in the browser. It is most commonly seen in environments where Nginx is configured as a reverse proxy for Neo4j, often due to specific Nginx settings related to buffering, content size, or client connection management.

 

This issue could also be caused by Nginx disk space limitations, issues with writing to log files, or permission problems. Investigating these issues in Nginx is beyond the scope of this article; however, restarting Nginx, checking startup errors, and addressing any flagged issues can be helpful first steps in diagnosing and resolving the problem.

You can adjust the Nginx configuration settings to ensure that content is buffered and delivered correctly. Disabling response buffering and increasing Proxy Buffer size and client_max_body_size in Nginx configuration can also help.

Isolating the issue:

To determine if Nginx is the source of the ERR_CONTENT_LENGTH_MISMATCH error, start by bypassing Nginx and accessing the Neo4j Browser directly. Use the Neo4j Browser URL on the advertised server address (e.g., http://<neo4j-server-ip>:7474) and check if the browser loads without error. Alternatively, you can use curl to verify the response from the Neo4j server:

curl http://<neo4j-server-ip>:7474 -v -k

If the Neo4j Browser loads or curl returns a successful response without the content length error, this indicates that Neo4j is functioning properly, and the issue likely lies within the Nginx configuration.

Additionally, examine the Neo4j server process and logs (debug.log and neo4j.log) to confirm that Neo4j is running smoothly without any internal errors. If no issues appear in Neo4j’s logs, it further suggests that the problem is isolated to the Nginx setup.