GoTo Opener encountered an error after initialization: The server deliveredthe unexpected content

It should be this one RafalW :

(DigiCert SHA2 Secure Server CA)

RafalW The 12057 error may be caused by file damage on the Windows system.  I would next try to finish the install / setup under a different User Account, and/or in safemode to rule out any conflicts.

Hi

Still have that problem.

This is standard computer, with standard hardware, any specific parts are connected to the system via network card (different that one used for internet connection).  We have similar systems installed on many sites and it's the only one where we have the issue. I know that the 1st answer is firewall but we were open firewall and it still doesn't work. 
From Logs it looks like the problem is with downloading server certificate:

17:18:21 1230 loading https://builds.getgocdn.com:443/builds/g2ax/1599/g2ax_customer_combined_dll_core_win32_x86.exe
17:18:21 1230 configuring request
17:18:21 1230 sending request
17:18:41 13F0 HttpSendRequestEx async error 12057
17:18:41 1230 error checking server certificate revocation;cnt=1
17:18:42 13F0 HttpSendRequestEx async error 12057
17:18:42 1230 error checking server certificate revocation;cnt=2
17:18:43 1398 HttpSendRequestEx async error 12057
17:18:43 1230 error checking server certificate revocation;cnt=3
17:18:44 13F0 HttpSendRequestEx async error 12057
17:18:44 1230 error checking server certificate revocation;cnt=4
17:19:20 1398 HttpSendRequestEx async error 12057
17:19:20 1230 error checking server certificate revocation;cnt=5
17:19:21 13C8 HttpSendRequestEx async error 12057
17:19:21 1230 error checking server certificate revocation;cnt=6
17:19:26 1230 I: downloaded 0 bytes in 64958 milliseconds (0.0 KiB/s)
17:19:26 1230 I: endpointDownloadMetrics: bytesDownloaded=0&cscErrorCount=6&displayedAuthUi=false&displayedUi=true&hostName=builds.getgocdn.com&requestUrl=https%3a%2f%2fbuilds.getgocdn.com%3a443%2fbuilds%2fg2ax%2f1599%2fg2ax_customer_combined_dll_core_win32_x86.exe&resolvedHostAddr=78.108.120.124&result=ECOsInetError.eSEC_CERT_REV_FAILED&timeBlockedInUi=4492&timeToConnect=0&timeToDownload=0&totalTime=64958
17:19:26 1230 E: [downloadEndpoint] completed: 14057 (ECOsInetError::eSEC_CERT_REV_FAILED), The API HttpSendRequestEx failed with code 12057.
Error returned at , taskdownload.cpp:218
Error occurred at , downloaderapp.cpp:1844
Error occurred at , downloaderapp.cpp:1791
17:19:26 1230 I: [completeInstall] started
17:19:26 1230 I: [leaveSingleInstance] started
17:19:26 1230 I: [startSendTelemetry] started
17:19:26 1230 I: [notifyUserIfFatalError] started
17:19:26 1230 E: flow error (not displayed):
(14057) "ECOsInetError::eSEC_CERT_REV_FAILED"
The API HttpSendRequestEx failed with code 12057.
Error returned at , taskdownload.cpp:218
Error occurred at , downloaderapp.cpp:1844
Error occurred at , downloaderapp.cpp:1791
17:19:26 1230 E: displaying error:
GoTo Opener encountered an error:
The download server builds.getgocdn.com is untrusted.
Failed to download GoToAssist from our servers.

I really don't know how to solve the issue. If you give me any advise it would be appreciated.

Rafal

RafalW If this is an embedded windows version, can you be specific about the hardware in use?  Is it some sort of customized endpoint?

What operating system is being affected?

Windows 7 Embedded

Which browser versions were tested?

Firefox Portable and Internet Explorer

If locally connected to the network, have you tested safemode for anything unseen that may be blocking the connection?
No

RafalW  What operating system is being affected?

Which browser versions were tested?

If locally connected to the network, have you tested safemode for anything unseen that may be blocking the connection?

Yes, I started it on my laptop connected to the same router and GoTo Opener run with no issues.
There is no any firewall or antyvirus running on a computer which has the problem. Also I'm logged in as an Administrator.

RafalW  Sorry about that.  Have you tried accessing fastsupport.com from any other computers on the same network to rule out a firewall problem?