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ECONNREFUSED
ECONNREFUSED means the connection attempt received a decisive rejection rather than simply waiting without a response. For a TCP stream connection, a common reason is that no process is listening on the target address and port. The TCP specification defines reset processing for attempts that do not match an existing connection; operating systems expose that outcome through their socket API.
The error does not prove that the destination host is down. It can also result from a service that is stopped, bound only to loopback or another interface, behind an unhealthy load balancer, or intentionally rejected by a firewall or proxy. UDP applications can see a similar result after the network reports that no receiver is associated with the destination.
Useful checks
- Log the resolved IP address and port, not only the original hostname.
- Verify the server listener, its bind address, and whether a reverse proxy is forwarding to the correct upstream port.
- Compare a local refusal with a timeout: an immediate refusal suggests a reachable endpoint that rejected the attempt; a timeout has different causes.
- Retry only when service startup or failover is an expected condition, and use bounded backoff.
About “What is” service
Many of users are faced with the problem of interpreting errors that occur during the work of operating systems. In some cases, the operating system reports that an error has occurred and displays only an integer error code value. Often it is difficult to even roughly understand the cause of the error from the information given out. Our “what is” service contains a database of errors in Windows, Linux, Macos and Solaris operating systems. The database contains tens of thousands of values. In most cases, the online service will be able to help with the definition of the short name of the error and its detailed description.
Categories
Current version of service supports following types of error and status codes:
| NTSTATUS | Many kernel-mode standard driver routines and driver support routines use the NTSTATUS type for return values. Additionally, drivers provide an NTSTATUS-typed value in an IRP’s IO_STATUS_BLOCK structure when completing IRPs. The NTSTATUS type is defined in Ntdef.h, and system-supplied status codes are defined in Ntstatus.h. |
| Win32 error | Win32 error codes MUST be in the range 0x0000 to 0xFFFF, although Win32 error codes can be used both in 16-bit fields (such as within the HRESULT type specified in section in this article) as well as 32-bit fields. Most values also have a default message defined, which can be used to map the value to a human-readable text message; when this is done, the Win32 error code is also known as a message identifier. |
| HRESULT | HRESULT is a data type used in Windows operating systems, and the earlier IBM/Microsoft OS/2 operating system, to represent error conditions, and warning conditions. The original purpose of HRESULTs was to formally lay out ranges of error codes for both public and Microsoft internal use in order to prevent collisions between error codes in different subsystems of the OS/2 operating system. HRESULTs are numerical error codes. Various bits within an HRESULT encode information about the nature of the error code, and where it came from. HRESULT error codes are most commonly encountered in COM programming, where they form the basis for a standardized COM error handling convention. |
| HTTP Status Code | Hypertext Transfer Protocol (HTTP) response status codes. Status codes are issued by a server in response to a client’s request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, and some additional codes used in some common applications of the HTTP. The first digit of the status code specifies one of five standard classes of responses. The message phrases shown are typical, but any human-readable alternative may be provided. |
| errno | Integer value, which is returned by system calls and some library functions in the event of an error to indicate what went wrong. errno is defined by the ISO C standard to be a modifiable lvalue of type int, and must not be explicitly declared; errno may be a macro. errno is thread-local; setting it in one thread does not affect its value in any other thread. |
| Kern Return | Apple Kernel return codes. |
| Ipp Status | The IppStatus constant enumerates the status values returned by the Intel IPP functions, indicating whether the operation is error-free. |
Source code
The service is based on the open source library AllStat. Its sources are available on our git server. We will be grateful for your participation in the finalization of the library and ideas for the development of the service. You can also download ErrorLookup utility and libraries from our site.