Upgrading 1.12.1 to 2.1.5

[bramanis]

So I almost successfully upgraded the 1.12.1 version to the current latest, 2.1.5 version. Atleast the upgrade process went smooth. Now I can't open my page, although I followed the documentation.

I get the following error running the page via command line:

# php index.php
Fatal error: require_once(): Failed opening required '/www/apache/domains/www.domain.tld/htdocs/lib/classes/class ... iables.php' (include_path='.:/usr/local/php56/share/pear') in /www/apache/domains/www.domain.tld/htdocs/lib/classes/class.CmsObject.php on line 38

After commenting out the line 38, I get this:
Fatal error: Cannot redeclare class CmsContentTypePlaceholder in /www/apache/domains/www.domain.tld/htdocs/lib/classes/class.CmsObject.php on line 466

In the webserver error logs there's this:
[Tue Oct 04 15:07:39.242497 2016] [fcgid:warn] [pid 39612] [client 194.204.13.125:55673] mod_fcgid: stderr: PHP Fatal error: Cannot redeclare class CmsContentTypePlaceholder in /www/apache/domains/www.domain.tld/htdocs/lib/classes/class.CmsObject.php on line 465

I googled for these and didn't end up with something relevant. Could someone please assist me?

[Rolf]

it is probably caused by a third party module, plugin or UDT...
Check these one by one by exclusion.

Posting System Information will also help us, help you.

[bramanis]

it is probably caused by a third party module, plugin or UDT...
Check these one by one by exclusion.

Posting System Information will also help us, help you.

Is the exclusion done by editing a configuration file? I can not access either the admin neither the public site.

I'm unable to find anything about it in the documentation.

[velden]

Disabling modules can be done by renaming their folder in the /modules folder (e.g. by using your hosting filemanager of ftp/ssh client).

BTW: Extensions -> Modules has an 'Active' column too which you can use to disable a module. BUT I'm not sure if that has the same effect to be honest.

Please post System Information too. Good change someone sees a suspicious module.

Site Admin > System information > 'View Text Report (suitable for copying into forum posts)'

[bramanis]

Disabling modules can be done by renaming their folder in the /modules folder (e.g. by using your hosting filemanager of ftp/ssh client).

BTW: Extensions -> Modules has an 'Active' column too which you can use to disable a module. BUT I'm not sure if that has the same effect to be honest.

Please post System Information too. Good change someone sees a suspicious module.

Site Admin > System information > 'View Text Report (suitable for copying into forum posts)'

I'll repeat - I can not access the site admin. Throws the same error. I'll try renaming the module folders.

[bramanis]

Disabling modules can be done by renaming their folder in the /modules folder (e.g. by using your hosting filemanager of ftp/ssh client).

BTW: Extensions -> Modules has an 'Active' column too which you can use to disable a module. BUT I'm not sure if that has the same effect to be honest.

Please post System Information too. Good change someone sees a suspicious module.

Site Admin > System information > 'View Text Report (suitable for copying into forum posts)'

I'll repeat - I can not access the site admin. Throws the same error. I'll try renaming the module folders.

That helped - the CMSDumper module caused problems. Cheers