Time to upgrade! NAM is scheduled for end of support. It's time to move to Dynatrace our all-in-one software intelligence platform.

Web - errors

NAM Console ► Deployment ► Manage devices, NAM Probe Configuration ► Open configuration, Global ► Front-End Monitoring ► Web ► Errors

You can configure the contents of HTTP error categories on NAM Probes that will feed your report server. The settings are global, which means that they apply to all analyzers reporting information on HTTP errors: HTTP, Oracle Forms, XML, and SOAP.


The NAM Probe is able to deliver information on seven HTTP error categories, five of which have configurable contents:

  • HTTP Authentication errors (default: 401 and 407)
  • HTTP Not Found errors (default: 404)
  • HTTP Custom Client errors 1 (4xx)
  • HTTP Custom Server errors 1 (5xx)
  • HTTP Custom Server errors 2 (5xx)

The two remaining groups contain HTTP errors that do not fall into any of the above categories: HTTP Other Client errors (4xx) and HTTP Other Server errors (5xx).

As the result of the assignment, the NAM Server reports the HTTP errors using the following metrics:

The number of observed HTTP client errors (4xx) and server errors (5xx).

This total can be broken down as follows.

4xx HTTP client errors

The sum of all HTTP client errors (4xx).

This includes 4 categories of errors (4xx), by default HTTP Unauthorized (401, 407) errors, HTTP Not Found (404) errors, custom client (4xx) errors and Other HTTP (4xx) errors. The contents of the first 3 categories can be configured by users.

However, there are two types of the 4XX errors that are of particular importance: errors 401 related to server-level authentication, and errors 404 indicating requests for non-existent content. These two error types are reported separately, by specific metrics.

401 Unauthorized

The server reports this error when user's credentials supplied with request do not satisfy page access restrictions. The HTTP server layer, not the application layer, reports 401 errors.

The NAM Probe will report on "Unauthorized" errors only if server-level authentication has been configured. This is common practice for sites that are comfortable with very basic user access policies. Most commercial-grade applications do not rely on server-level authentication (e.g. most of online banking applications or online shopping), but rather authenticate users on the application layer. In such cases, even if authentication fails, the server will typically send 200 OK responses and authentication error information will be explained in page content. So this kind of error is not very common in commercial sites.

404 Not Found

The server reports "Not Found" errors when it cannot fulfill client request for a resource. Usually it happens due to malformed URL, which directs to a non-existing page or image.

Such a URL request may result from a user, who misspelled the URL, trying to access a URL that the user stored in his "Favorites" folder a long time ago, or some other mistake. Malformed URLs may also exist in invalid or incorrectly designed Web pages so the error will be reported by browsers trying to load such a page.

A significant and constant number of these errors usually indicates that some pages on the server have design-related or link validation issues. In some cases, 404 errors result from the server overload. It is good practice to check whether the percentage of errors is load-related.

401, 407 HTTP unauthorized errors

The number of observed custom HTTP authentication related errors.

These include "HTTP 401 Unauthorized" and "HTTP 407 Proxy authentication required" errors.

  • HTTP servers generate "401 Unauthorized" errors when anonymous clients are not authorized to view the requested content and must provide authentication information in the WWW-Authenticate request header. The 401 errors are similar to "403 Forbidden" errors, but they are used when authentication is possible but it has failed or not yet been provided.
  • The 407 error is basically similar to 401, but it indicates that the client should first authenticate with a proxy server.

The NAM Probe will report these errors only if the server-level authentication has been configured. Simple and basic user access policies are common in Web sites that do not store user-sensitive and/or business critical information.

Most commercial-grade applications, based on HTTP, such as home banking applications or online shopping sites, rely on the application-level authentication rather than the server-level authentication. Such applications are designed in the way that even if the user authentication fails, the HTTP server usually sends the 200 OK response code and the authentication error message in the page content. Therefore, the 401 Unauthorized and 407 Proxy authentication required error codes are quite rare in commercial environments.

404 HTTP not found errors

These include the observed custom HTTP 404 Not found errors.

HTTP client errors - category 3 (default name)

The number of HTTP custom client errors (4xx). By default, there is no specific error type assigned here.

HTTP other client errors (4xx)

The number of HTTP other client errors (4xx).

There are four categories of HTTP client errors (4xx), of which three can be configured by users. By default, the first category includes HTTP Unauthorized (401, 407) errors, the second category - HTTP Not Found (404) errors. The third category contains no default error types assigned, and can be configured by a user. Finally, a group of HTTP Other (4xx) errors contains all errors that do not fall into any other client errors category.

The number is calculated based on the formula: [HTTP errors 4xx] - [HTTP Not Found errors 404] - [HTTP Not Authorized (401+ 407)] - [HTTP errors configured by user].

5xx HTTP server errors

The number of observed HTTP server errors (5xx).

The response status codes 5xx indicate cases, in which the Web server is aware that there was a server error or it is incapable of performing the request. Such error presence usually means that the Web server does not function as intended. The following 5xx errors are defined by the HTTP protocol standards:

  • 500 Internal Server Error - The server encountered an unexpected condition, which prevented it from fulfilling the request.
  • 501 Not Implemented - The server does not support the functionality required to fulfill the request.
  • 502 Bad Gateway - The server received an invalid response from a back-end application server.
  • 503 Service Unavailable - The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.
  • 504 Gateway Timeout - The server did not receive response from a back-end application server.
  • 505 HTTP Version Not Supported - The server does not support the HTTP protocol version that was used in the request message.

HTTP server errors – category 1 (default name)

The number of custom HTTP server errors (5xx), category 1. By default, there are no specific error types assigned to this category.

HTTP server errors – category 2 (default name)

The number of custom HTTP server errors (5xx), category 2. By default, there are no specific error types assigned to this category.

HTTP other server errors (5xx)

The number of HTTP server errors (5xx) that do not fall into categories 1 or 2 of custom HTTP server errors (5xx).

Categories with no status codes assigned cannot have their names edited by a user of a report server.

Configuration of HTTP error codes

All NAM Probes connected to one NAM Server must have identical configurations for HTTP errors. If you have already configured HTTP errors on one of your NAM Probes, you can import or copy the configuration settings from this device to the other devices. The configuration is stored in the applications.xml file.

You can manage the errors listed on the HTTP Errors screen.

  • To add a new error code, right-click the table corresponding to the error group to modify and select Add. This will automatically add a 400 or 500 code to the group of client or server errors, depending on which group you are editing. To modify the default status code number, click it to make the text editable, and then type the replacement number.
  • To modify an error code, click the code number to make the text editable and type a new code.
  • To delete an existing error code, right-click a code number and select Delete from the context menu.