This question has been answered by zurie. See the first response.
[2018-03-08 15:15:43] (ERROR @ /home/zurie/public_html/mysubdomainsite/core/model/modx/modmanagerresponse.class.php : 190) PHP warning: Parameter 1 to modManagerController::getInstance() expected to be a reference, value given [2018-03-08 16:02:00] (ERROR @ /home/zurie/public_html/mysubdomainsite/core/xpdo/om/xpdoobject.class.php : 240) Error 42S22 executing statement: Array ( [0] => 42S22 [1] => 1054 [2] => Unknown column 'modUser.createdon' in 'field list' )
If you're looking to install a separate modx installation so that it is accessible from a subdomain, or even another domain completely, then you should setup a different hosting environment to cater for that.
Additionally you could look into setting up multiple contexts to manage various sites from the one modx manager - where you would point all domains to the same document route for example.
That being said I do have a lab that holds various development sites within different subfolders and that works fine. Ensure that each has their own htaccess file and that the core/config paths are setup correctly.
ext-base.js:21 GET http://mysite.com/connectors/?_dc=1520527689662&action=workspace%2Fpackages%2FgetAttribute&attributes=license%2Creadme%2Cchangelog%2Csetup-options%2Crequires&signature=upgrademodx-1.5.5-pl&HTTP_MODAUTH=modx5aa15e8b102841.82994802_15aa15e980daca3.64192481 500 (Internal Server Error) i @ ext-base.js:21 request @ ext-base.js:21 request @ ext-all.js:21 install @ package.grid.js:239 onClick @ package.grid.js:219 I @ ext-all.js:21 11:48:09.835 ext-base.js:21 XHR failed loading: GET "http://mysite.com/connectors/?_dc=1520527689662&action=workspace%2Fpackages%2FgetAttribute&attributes=license%2Creadme%2Cchangelog%2Csetup-options%2Crequires&signature=upgrademodx-1.5.5-pl&HTTP_MODAUTH=modx5aa15e8b102841.82994802_15aa15e980daca3.64192481".
Request URL:https://mysite.com/connectors/index.php Request Method:POST Status Code:403 Forbidden Remote Address: removeIPaddressHere:443 Referrer Policy:no-referrer-when-downgrade
2018-03-08 16:47:01 mysite.com myIPADDRESSHERE CRITICAL 404 942170: Detects SQL benchmark and sleep injection attempts including conditional queries Hide Request: POST /connectors/index.php Action Description: Warning. Justification: Pattern match "(?i:(?:(select|;)\\s+(?:benchmark|if|sleep)\\s*?\\(\\s*?\\(?\\s*?\\w+))" at ARGS:handler.