Here you will find a list of common library problems and possible solutions to overcome them.
This is a common issue, usually triggered by an error in libcURL. There are several reasons for it, but we'll list the most common ones. If you bump into it, check the exception code and read the corresponding entry.
This error happens when libcURL tries to use a protocol it doesn't have support for. Either because the SSL/TLS library doesn't support it (GnuTLS), or because it was simply disabled at build time by the vendor (Ubuntu).
In the majority of cases, it's because CURL_SSLVERSION_SSLv2 is being set, or even CURL_SSLVERSION_DEFAULT (which may default to the former), but it should always be confirmed from the error message.
Try using CURL_SSLVERSION_SSLv3 instead.
For more information about the security protocols supported by libcURL, refer to the SSL library comparison list
This is the error when the protocol handshake fails. The error message will most likely be the following:
Unknown SSL protocol error in connection to accounts.accesscontrol.windows.net:443
If CURL_SSLVERSION_SSLv2 or CURL_SSLVERSION_SSLv3 are being used, try using CURL_SSLVERSION_TLSv1_0 instead.
Note that CURL_SSLVERSION_TLSv1_0 has only been available since PHP 5.5.19/5.6.3 and cURL 7.34+.
The error message associated with this error code might be:
GnuTLS recv error (-9): A TLS packet with unexpected length was received.
This happens when libcURL is built against GnuTLS and the fact that this library is more strict when dealing with the TLS protocol.
The GnuTLS mailing list has an explanation about it:
Several sites terminate the TLS connection without following the TLS protocol (i.e. sending closure alerts), but rather terminate the TCP connection directly. This is a relic of SSLv2 and it seems other implementations ignore this error. GnuTLS doesn't and thus prints this error.
Given that this is a mix of SharePoint not following the TLS protocol correctly and GnuTLS being too strict about it, there's not much that can be done except for using a different PHP/libcURL version.
If you get other cURL errors, check the libcURL error list.