HTTP client: send method failed with return code SY_SUBRC &1

What causes this issue?

While data was send by HTTP connection, an error occurred.

System Response

The connection was closed, the processing was cancelled.

How to fix this error?

Check the documentation for information about errors during HTTP
communication.

Procedure for System Administrators

Method IF_HTTP_CLIENT~SEND of class CL_HTTP_CLIENT returned the error
code &V1&
The error codes can be mapped to the following exceptions of the method:
1 = HTTP_COMMUNICATION_FAILURE
2 = HTTP_INVALID_STATE
3 = HTTP_PROCESSING_FAILED
4 = HTTP_INVALID_TIMEOUT

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.