Updated to 4.13.1 last night, woke up to a offline server and this - see attached for more detail
[2016.09.30-05.36.42:444][493]LogEngine:Warning: TimerManager 000000000BB7EC40 dump ended
[2016.09.30-05.36.42:444][493]LogWindows:Error: === Critical error: ===
[2016.09.30-05.36.42:444][493]LogWindows:Error:
[2016.09.30-05.36.42:444][493]LogWindows:Error: Fatal error!
[2016.09.30-05.36.42:444][493]LogWindows:Error:
[2016.09.30-05.36.42:444][493]LogWindows:Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x20640000
[2016.09.30-05.36.42:444][493]LogWindows:Error:
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FCurlHttpRequest::DebugCallback() [d:\4_13_1\engine\source\runtime\online\http\private\curl\curlhttp.cpp:420]
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FCurlHttpRequest::StaticDebugCallback() [d:\4_13_1\engine\source\runtime\online\http\private\curl\curlhttp.cpp:262]
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!Curl_write_plain()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!Curl_debug()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!Curl_add_buffer_send()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!Curl_http()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!Curl_do()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!curl_multi_wait()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!curl_multi_perform()
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FCurlHttpThread::HttpThreadTick() [d:\4_13_1\engine\source\runtime\online\http\private\curl\curlhttpthread.cpp:28]
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FHttpThread::Run() [d:\4_13_1\engine\source\runtime\online\http\private\httpthread.cpp:135]
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FRunnableThreadWin::Run() [d:\4_13_1\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:74]
[2016.09.30-05.36.42:444][493]LogWindows:Error: ZTASERVER.exe!FRunnableThreadWin::GuardedRun() [d:\4_13_1\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:31]
[2016.09.30-05.36.42:444][493]LogWindows:Error: kernel32.dll
[2016.09.30-05.36.42:444][493]LogWindows:Error: ntdll.dll
[2016.09.30-05.36.42:444][493]LogWindows:Error: ntdll.dll
[2016.09.30-05.36.42:444][493]LogWindows:Error:
[2016.09.30-05.36.42:444][493]LogWindows:Error: Crash in runnable thread HttpManagerThread
[2016.09.30-05.36.42:449][493]LogExit: Executing StaticShutdownAfterError
[2016.09.30-05.36.42:449][493]LogWindows: FPlatformMisc::RequestExit(1)