## Why Does \'curl error 18: transfer closed with outstanding read data remaining\' Happen?

Error Handling in Curl: Understanding and Resolving "curl error 18"

When attempting to retrieve data using the curl library, you may occasionally encounter the cryptic error 18: "transfer closed with outstanding read data remaining." This error indicates that the connection was terminated before all expected data could be received. The missing data can result in incomplete results.

The peculiarity of this error lies in its absence when the CURLOPT_RETURNTRANSFER option is set to false, indicating that the data is not returned by the curl_exec function but displayed directly.

Understanding the Cause

The error message directly reflects the behavior of the libcurl library. When receiving a chunked encoding stream, curl has knowledge of the remaining data within each chunk. If the connection prematurely closes, the library detects an incomplete final chunk, triggering the error.

Potential Workarounds

While it's important to acknowledge that the error may stem from server or network issues, there is a possible workaround:

• Manually issuing an HTTP 1.0 request instead. By doing so, chunked encoding is avoided, which could resolve the issue.

However, it's crucial to note that this approach is not guaranteed to eliminate the error entirely. If the problem persists, it's advisable to investigate potential server or network-related causes.

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