Web Request Events by Status monitors web requests grouped by HTTP status code to help identify application errors, failed requests, and unexpected changes in web activity. By tracking the status codes returned by the web server, this alert helps detect issues that may affect website availability, API functionality, or the user experience.
An increase in a specific HTTP status code may indicate an application error, a backend failure, a configuration issue, or a resource bottleneck, even when the website appears to be operating normally.
Symptoms:
Web requests are returning unexpected HTTP status codes or experiencing an increase in failed requests. Users may encounter error messages, failed operations, authentication problems, or difficulties accessing application features.
Impact: Medium
Unexpected HTTP status codes can disrupt business operations and degrade the user experience. Repeated server errors or a high rate of failed requests may prevent users from accessing critical application functions, such as ERP operations, API services, or order processing. The impact depends on the type of error, its frequency, and the business importance of the affected requests.
Expected behavior:
HTTP status codes vary according to application functionality, user activity, authentication requirements, and the resources being requested. Some status codes, such as 200 (OK), indicate successful requests, while others may represent normal application behavior. For example, 301 and 302 indicate redirects, 401 may occur during authentication, and 404 may be expected when a requested resource does not exist.
Unexpected or recurring increases in error status codes, particularly 5xx server errors, may indicate an underlying application, database, backend, or infrastructure issue. Expected behavior should be evaluated according to the application’s normal request patterns and business requirements.
Investigate recurring errors, sudden increases in failed requests, or unusual changes in the distribution of HTTP status codes. Pay particular attention to 5xx server errors and unexpected increases in 4xx client errors, which may indicate problems affecting application availability or functionality.
Possible causes of Web Events by Status alerts
Application errors caused by bugs or exceptions in the application. Priority: Medium
Application errors may cause web requests to fail, resulting in HTTP 5xx status codes or other unexpected responses. These errors can occur following code changes, unhandled exceptions, invalid input, or failures in application logic. Repeated errors may prevent users from completing specific operations.
Problem identification:
Identify the URLs returning errors and determine whether the failures are recurring or associated with specific application operations.
- Identify the affected URLs and check the HTTP status codes returned by the requests.
- Review IIS logs and application logs for exceptions, error messages, and recurring failures associated with the affected URLs.
- Check whether the errors started after a recent application deployment or configuration change. Consult the application team to identify and resolve the underlying issue.
Recommended action :
Fix the application errors causing the affected URLs to fail. Correct unhandled exceptions, invalid input handling, or application logic issues, and verify that the affected requests return the expected HTTP status codes. If the errors began after a recent deployment, consider rolling back the change until a fix is available.
2- Backend service or database failures preventing successful request processing. Priority: High
Web applications often depend on databases and backend services to process requests. If a database becomes unavailable, queries time out, or a dependent service fails, the application may return HTTP 5xx errors or gateway errors such as 502 Bad Gateway and 504 Gateway Timeout. These failures can interrupt important application functions even when the web server itself remains available.
Problem identification:
Determine whether HTTP errors coincide with database performance problems, unavailable backend services, or request timeouts.
- Identify the status codes and review the associated timestamps to establish when the errors occur.
- Check database availability, query execution times, blocking, and resource utilization. Review backend service logs for connection failures and timeouts.
- Correlate the errors with database or backend activity and consult the DBA or application team to identify the underlying cause.
Recommended action :
Restore the availability and performance of the affected database or backend service. Optimize slow queries, resolve blocking, correct connectivity issues, or address service failures as appropriate. Verify that the application can process requests successfully after the fix.
3- Insufficient server resources causing failed or rejected web requests. Priority: High
High CPU utilization, memory pressure, or other server resource bottlenecks can prevent a web application from processing requests efficiently. Under heavy load, requests may time out, application pools may become unresponsive, and users may receive HTTP 5xx errors. In some cases, excessive incoming traffic may also result in HTTP 503 Service Unavailable responses.
Problem identification:
Check whether increases in HTTP 5xx errors coincide with high server resource utilization or IIS application pool problems.
- Identify when error rates increase and determine which HTTP status codes are affected.
- Review CPU and memory utilization, disk activity, and IIS application pool status during the affected periods.
- Identify resource-intensive processes or services and determine whether the server is overloaded or an application pool is stopping or becoming unresponsive.
Recommended action :
Resolve the resource bottleneck by optimizing resource-intensive processes, investigating abnormal application behavior, or increasing server capacity when necessary. If an IIS application pool is stopping, identify and correct the underlying cause before restarting it. Verify that the error rate decreases after the changes.
4- Incorrect configuration or recent changes causing HTTP errors. Priority: Medium
Changes to IIS settings, application configuration, authentication, routing, or application code can cause requests to fail. Depending on the issue, users may receive status codes such as 401 Unauthorized, 403 Forbidden, 404 Not Found, or 500 Internal Server Error. These errors may affect specific application functions or a large portion of the website.
Problem identification:
Determine whether unexpected HTTP status codes began after a deployment, configuration change, or update to the web server.
- Identify the most frequent unexpected status codes and determine which application functions are affected.
- Review IIS logs and configuration settings. For 401 or 403 errors, check authentication and permissions; for 404 errors, verify URL routing and resource availability.
- Compare the timing of the errors with recent deployments or configuration changes. Consult the application or infrastructure team to validate the relevant settings.
Recommended action :
Correct the configuration or deployment issue responsible for the unexpected status codes. Verify IIS settings, authentication, permissions, routing, and application configuration as relevant. If the issue began after a recent change, consider rolling back the change or applying a correction, then confirm that requests return the expected status codes.
