Error in the push function.

[Amirali Hossein]

Hello,

How should I resolve "Error in the push function."?

```
$ sudo openconnect -v -c pkcs11:id=%01 --user=<snip> vpn.example.com
POST https://vpn.example.com/
Attempting to connect to server <snip>:443
Connected to <snip>:443
Using PKCS#11 certificate pkcs11:id=%01;type=cert
PIN required for PIV Card Holder pin (PIV_II)
Enter PIN:
Using PKCS#11 key pkcs11:<snip>
Using client certificate <snip>
SSL negotiation with vpn.example.com
SSL connection failure: Error in the push function.
Failed to open HTTPS connection to vpn.example.com
Failed to obtain WebVPN cookie
```

VPN Log:

```
POST https://vpn.example.com/
Attempting to connect to server <snip>:443
Connected to <snip>:443
SSL negotiation with vpn.example.com
Server certificate verify failed: signer not found
Connected to HTTPS on vpn.example.com
Got HTTP response: HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Transfer-Encoding: chunked
Cache-Control: no-store
Pragma: no-cache
Connection: Keep-Alive
Date: Tue, 16 Nov 2021 19:39:06 GMT
X-Frame-Options: SAMEORIGIN
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Aggregate-Auth: 1
HTTP body chunked (-2)
Server requested SSL client certificate; none was configured
POST https://vpn.example.com/
Got HTTP response: HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Transfer-Encoding: chunked
Cache-Control: no-store
Pragma: no-cache
Connection: Keep-Alive
Date: Tue, 16 Nov 2021 19:39:06 GMT
X-Frame-Options: SAMEORIGIN
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Aggregate-Auth: 1
HTTP body chunked (-2)
XML POST enabled
POST https://vpn.example.com/
Got HTTP response: HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Transfer-Encoding: chunked
Cache-Control: no-store
Pragma: no-cache
Connection: Keep-Alive
Date: Tue, 16 Nov 2021 19:39:31 GMT
X-Frame-Options: SAMEORIGIN
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Aggregate-Auth: 1
HTTP body chunked (-2)
```

Thanks.