While performing URL monitoring in OpManager, there are a few common errors encountered when adding and monitoring URLs. The error codes and measures needed to resolve those issues are as follows:
| Response status code | Description | Ways to resolve |
| 400 | The request could not be understood by the server due to malformed syntax. | Verify the URL and parameters configured in the HTTP URL monitor. |
| 401 | Authentication required. Authorization credentials are either missing or incorrect. | Update the HTTP monitor settings with valid credentials under “Advanced Settings.” |
| 402 | This code is reserved for future use. | No action needed. Not applicable. |
| 403 | This URL is forbidden. | Ensure that the OpManager server IP is whitelisted on the target server and that access permissions are configured. |
| 404 | The server has not found anything matching the Request-URI. | Double-check the URL path and ensure the resource exists. |
| 405 | The HTTP method is not allowed for the requested resource. | Change the request method (e.g., GET/POST) in the HTTP monitor configuration. |
| 406 | Content not acceptable according to the Accept headers. | Adjust the Accept headers under advanced HTTP monitor settings if supported. |
| 407 | Proxy Authentication Required. | Configure proxy settings and authentication in OpManager's proxy configuration under Admin → Proxy Settings. |
| 408 | Request Timeout. | Increase timeout threshold in the HTTP monitor and ensure network latency is within limits. |
| 409 | Conflict. | Review application/server logs to understand the conflict. May not be directly configurable via OpManager. |
| 410 | The requested resource is no longer available. | Update the monitor with a current, valid URL. |
| 411 | Missing Content-Length header. | Manually define headers if needed using advanced HTTP settings in the monitor configuration. |
| 414 | Request-URI Too Long. | Simplify the URL or reduce query parameters where possible. |
| 415 | Unsupported Media Type. | Ensure that the content-type used in the request matches what the server supports. |
| 500 | Internal Server Error. | Check the target application/server logs. This is an issue on the destination server. |
| 502 | Bad Gateway. | Ensure the upstream server is reachable and not returning invalid responses. |
| 503 | Service Unavailable. | Retry later. Configure alerts in OpManager to notify when the service is restored. |
| 504 | Gateway Timeout. | Extend timeout duration in monitor settings and verify network routing or upstream availability. |
| 505 | HTTP Version Not Supported. | Modify the request to use a supported HTTP version (1.1 recommended in most HTTP monitors). |
Other possible errors:
| Error Message | Description | Ways to resolve |
|---|---|---|
| Input/Output transfer has been terminated because the thread performing it was interrupted. | This is an issue in the user's environment. | |
| Certificates does not conform to algorithm constraints. | The latest Java version (Java 8) disabled a few weak signature algorithms to improve security. The mentioned URL is using one such weak algorithm. You can view the list of accepted cipher suites in Java 8 here.Note that only OpManager builds later than 12.4 support Java 8, so it might be necessary to upgrade your OpManager installation to the latest version. | This issue needs URL-side troubleshooting in order to be fixed. |
| Certificate required to access the URL is not imported into OpManager. | The necessary certificate of the site needs to be imported into OpManager. | Go to Settings → Security Settings → Trusted Certificates. Here, you can import the certificate of the URL. Note that this option is available only in OpManager 12.4 and above. |
| Peer not authenticated. | 'SSL Error due to Peer not authenticated' - this exception occurs when the connection made to the server URL is not from the authenticated client. This may be due to wrong SSL version, no certificate being provided, the particular cipher suite being used not supporting authentication or no peer authentication being established during SSL handshaking. | This issue needs URL-side troubleshooting in order to be fixed. |
| Missing WWW-Authenticate header. | 'WWW-Authenticate header' is missing from URL response. | This issue needs URL-side troubleshooting in order to be fixed. |
| NTLM version of URL. | The latest version of the OpManager supports NTLM version 1.0 and 1.1. | Refer the Microsoft help page to know about NTLM versions. |
| URL might be using Kerberos Authentication. | Currently, OpManager does not support Kerberos Authentication | NA |
| Inappropriate Proxy Configuration. | Any/all of your proxy configuration details such as server or credentials are wrong. | Check your proxy configuration details and configure them properly. |
| Please increase time-out value to resolve this issue. | URL timed out occurred. This issue happens in different situations like when target URL is absent, the IP/domain or port (i.e service) is down and so on. | Increase time-out of the URL in OpManager to resolve this issue. |
| Socket connection reset error occurred. | Commonly, this issue is caused by writing to a connection where the other end has already closed normally. In other words, it is an application protocol error. It can also be caused by closing a socket when there is unread data in the socket receive buffer. | This issue needs URL-side troubleshooting in order to be fixed. |