A customer contacted the Unihost support team because their website had suddenly become unavailable. The web server itself was running, but visitors could not access the application normally. The immediate objective was to determine whether the problem was caused by the web server, the application backend, or the connection between them, and restore the service as quickly as possible.<\/span><\/p>\n The first useful indicator came from the web-server logs. Nginx was returning HTTP 502 Bad Gateway errors. A 502 response usually means that the frontend web server is running but cannot successfully communicate with the backend service expected to process the request. In this case, the problem appeared after manual changes had been made to the Nginx configuration. The changes had broken request proxying between Nginx and the backend application. The website therefore remained reachable at the web-server level, but requests could no longer be passed correctly to the application behind it.<\/span><\/p>\n <\/p>\n 1. Checked the web-server logs<\/b><\/p>\n The support team reviewed the Nginx logs to identify the type of failure. The repeated 502 responses narrowed the investigation to the interaction between Nginx and the backend service.<\/span><\/p>\n 2. Reviewed the proxy configuration<\/b><\/p>\n The recently modified Nginx configuration was inspected. The analysis showed that the proxying rules no longer correctly forwarded requests to the backend application.<\/span><\/p>\n 3. Verified backend availability<\/b><\/p>\n Before changing the frontend configuration, the team checked that the backend application itself was available. This was important because correcting Nginx would not solve the incident if the application behind it was also unavailable. Once backend availability had been confirmed, the problem could be isolated to the web-server configuration.<\/span><\/p>\n 4. Corrected the Nginx configuration<\/b><\/p>\n The affected proxy settings were restored to a working state. The corrected configuration was validated before the web server was restarted.<\/span><\/p>\n 5. Restarted and tested the service<\/b><\/p>\n After applying the changes, Nginx was restarted and the website was tested again. Requests were successfully forwarded to the backend application and the site returned to normal operation.<\/span><\/p>\n A 502 error does not necessarily mean that Nginx itself has failed. The problem may be caused by an unavailable backend application, incorrect proxy settings, an incorrect backend address or port, an application-side failure, or communication problems between the frontend and backend. In this incident, checking the backend separately made it possible to avoid unnecessary changes to the application and focus directly on the broken proxy configuration.<\/span><\/p>\n The work included incident diagnostics, Nginx log analysis, reverse-proxy troubleshooting, backend availability testing, Nginx configuration correction, service restart, and post-recovery validation.<\/span><\/p>\n The website was restored without rebuilding the application or reinstalling the server. The cause of the outage was traced to manual changes in the Nginx proxy configuration. The affected settings were corrected, communication with the backend application was restored, and the site returned to normal operation.<\/span><\/p>\n <\/p>\n Results at a glance<\/b>: 502 error diagnosed, backend verified, Nginx proxy configuration repaired, website restored, unnecessary application changes avoided.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":" Initial situation A customer contacted the Unihost support team because their website had suddenly become unavailable. The web server itself was running, but visitors could not access the application normally. The immediate objective was to determine whether the problem was caused by the web server, the application backend, or the connection between them, and restore […]<\/p>\n","protected":false},"author":7,"featured_media":9201,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[],"class_list":["post-9200","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-case-study","has-post-title","has-post-date","has-post-category","has-post-tag","has-post-comment","has-post-author",""],"yoast_head":"\nTechnical Challenge<\/b><\/h2>\n
What the Unihost Team Did<\/b><\/h2>\n
Why the Troubleshooting Approach Mattered<\/b><\/h2>\n
Unihost Support Work<\/b><\/h2>\n
Result<\/b><\/h2>\n