SUPEE cart and shop issues

[Odyn]

Hey guys.

I am new in magento and I am digging into it to help my friends to solve their magento shop issues.

There are several issues which after SUPEE instalations broke their shop, they cannot register new user or cannot ad any product into cart.

What should I do first to solve this problem? Why they released something which doesnt work correctly?

[Mukesh Tiwari]

Hi @Odyn

Could you specify which patch your friend applied to magento site?

What are the error messages?

Any specific errors in log or exception files. 

[Odyn]

Hey,

Thank You for Your reply.

I try to gather some error logs and feedback from their store as soon as possible.

Probably they are not sure which SUPEE cause this error. I will reply here as soon as possible.

Is there any possibliy to roll back Magento updates? 

[Odyn]

Ok i got feedback and access to exceptions and system logs inside var/log of magento store.

If we are talking about SUPEE then he installed all of them without the newest from 20 february 2015.

[Odyn]

For example at first there are a lot of things inside log files I cut some of them first:

2015-01-27T10:30:01+00:00 ERR (3): Warning: DOMDocument::createTextNode() expects parameter 1 to be string, object given in /home/shop/domains/shopname.domain.com/public_html/app/code/local/Plugins/Pcmarket/Model/Xml.php on line 18
2015-01-27T10:30:01+00:00 ERR (3): Recoverable Error: Argument 1 passed to DOMNode::appendChild() must be an instance of DOMNode, null given, called in /home/shop/domains/shopname.domain.com/public_html/app/code/local/Plugins/Pcmarket/Model/Xml.php on line 38 and defined in /home/shop/domains/shopname.domain.com/public_html/app/code/local/Plugins/Pcmarket/Model/Xml.php on line 19

There is some issues with PC Market plugin.