App center connection failed

Hello everyone,
I am very new to UCS servers. I insttaled UCS as a new Domain controller OS on my Vmware ESXi.
Several times I tried to connect to App center but I got the following error"

There is a problem with the certificate of the App Center server ((’_ssl.c:645: The handshake operation timed out’,))

Thanks in advance

Please check date and time of your UCS instance. Certificats are “date-sensitive”.

Hi Mornsgrans
Thank you for your suggestion. But it didn’t work. any other solutions?

Do you have access from other computers to
Do you use a web-proxy (maybe with antivirus software)? It might be possible, that this will break the SSL encryption.

I don’t have access to Appcernter from other computers.
How can I make sure I am not behind the web-proxy? Forr tracing IP in cmd I use tracert command, is there any equivalent command on SSH? I stopped the antivirus consul. but I still do not have access.

Please help me with web interface now…I dont have access now. I think I did something wrong. Now I am can not open UCS from a web browser. :
I read from a forum it is related to Apache. I used this command but I got the following error:

root@ucs:~# systemctl status apache2
● apache2.service - The Apache HTTP Server
Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Tue 2021-02-16 15:47:38 +0330; 8s ago
Process: 10036 ExecStart=/usr/sbin/apachectl start (code=exited, status=1/FAILURE)
CPU: 72ms

Feb 16 15:47:38 ucs systemd[1]: Starting The Apache HTTP Server…
Feb 16 15:47:38 ucs apachectl[10036]: AH00526: Syntax error on line 23 of /etc/apache2/sites-enabled/default-ssl.conf:
Feb 16 15:47:38 ucs apachectl[10036]: SSLCertificateFile: file ‘/etc/myssl/cert.crt’ does not exist or is empty
Feb 16 15:47:38 ucs apachectl[10036]: Action ‘start’ failed.
Feb 16 15:47:38 ucs apachectl[10036]: The Apache error log may have more information.
Feb 16 15:47:38 ucs systemd[1]: apache2.service: Control process exited, code=exited status=1
Feb 16 15:47:38 ucs systemd[1]: Failed to start The Apache HTTP Server.
Feb 16 15:47:38 ucs systemd[1]: apache2.service: Unit entered failed state.
Feb 16 15:47:38 ucs systemd[1]: apache2.service: Failed with result ‘exit-code’.

I reinstalled Apache! Now I got Apache2 Debian Default Page when I insert UCS IP in web browser:

Apache2 Debian Default Page

his is the default welcome page used to test the correct operation of the Apache2 server after installation on Debian systems. If you can read this page, it means that the Apache HTTP server installed at this site is working properly. You should replace this file (located at /var/www/html/index.html) before continuing to operate your HTTP server.

How can I configure it for UCS?

Hi @alih,

You should really not do that. There are a lot of configuration packages involved in Univention and manually removing packages will only cause issues if you do not 100% know what you are doing. I would recommend to start over with a fresh installation.

And regarding your error message:

It seems you tried to configure a file/path for your ssl certificate that did not exist. Fixing the path or removing the faulty configuration option would usually result in a successful start again.

If you use Letsencrypt certificates, you must set the Apache settings in Univention registry to the Letsencrypt-certificates in folder /etc/univention/letsencrypt/
Otherwise please find the default self-signed certificates in /etc/univention/ssl/<my_ucs_FQDN>/

Thanks All, I reinstall a fresh UCS domain controller server. Now I have a new problem. I cann’t activate UCS lisence
“The activation of UCS failed. Please re-try to perform the the activation again via the user menu in the top right.”
My gateway connection and DNS is OK.

Did you test internet connection from UCS server, f.ex. ping on SSH console?

Dear friends,
I reinstalled UCS again and I came back to my first error:
There is a problem with the certificate of the App Center server . ((’_ssl.c:645: The handshake operation timed out’

I can ping from SSH.

Can you also


Do you get the error, if you call from annother computer in the same network/subnet?

In my opinion it is not an UCS related problem, but something in the connection to appcenter “breaks” the SSL.

TLS 1.3 is required

1- I get to same error from other computers.

2- I received these results from ping

64 bytes from ( icmp_seq=47 ttl=49 time=85.7 ms
64 bytes from ( icmp_seq=48 ttl=49 time=86.6 ms

what do you mean by “TLS 1.3 is required”?

This is my certificate setting it seems something is wrong because the location country is Germany while the state is US.
Could this error be related to this setting?

I just jave seen, that I cannot find any link to on my UCS server.
If I call the app-center, the address
is shown in the address field of my browser.

If I call I become redirected to Univention start page.

That is true. I see https://<my_ucs_server>/univention/management/#module=appcenter:appcenter:0: in my browser too. and If I call [] I am redirected to Univention start page.

Mates, Please HELP me!
I migrated from WIN Server to UCS to benefit from its good features now I don’t access to APP center.

I do not know, what you did, that you seem not get access to app center.

What are you doing with the addresses you mentioned above?

Just login into your UCS via browser, and goto “System- and domain-settungs” - “Software” - “App Center”.

Here is my Mikrotik Firewall connection list filtered by UCS server IP.
Does it make sense to you?