This solution contains invalid markup or elements that cannot be deployed as part of a sandboxed solution. Solution manifest for solution 'cc218449-78b3-4430-b401-4884977560e2' failed validation, file manifest.xml, line 11, character 4: The element 'Solution' in namespace 'http://schemas.microsoft.com/sharepoint/' has invalid child element 'TemplateFiles' in namespace 'http://schemas.microsoft.com/sharepoint/'. List of possible elements expected: 'FeatureManifests, ActivationDependencies' in namespace 'http://schemas.microsoft.com/sharepoint/'. Troubleshoot issues with Microsoft SharePoint Foundation. Correlation ID: oplh6595a-a6hg-416f-a85f-a173bp03dda6 Date and Time: 30/10/2013 13:33:18

By looking at this bug you may get shocked and may not understand why this is happening. I can say, you have developed a wsp of farm solution, not the sandboxed solution  using visual studio and added some OOTB webparts such as visual webparts and trying to deploy the solution via solution gallery directly on to the sharepoint site.

It is so simple.Understand that, when you create a .wsp file using visual studio, you deploy as farm solution. But when you try to deploy the same solution from site settings-> solution gallery, you deploy it as sand boxed solution. In this situation ,the "TemplateFiles" elements refers to the items that will be copied into the web servers.This is allowed only in farm solutions, not in sandboxed solutions.

I suggest you guys to deploy the solution either using stsadm command or powershell command, so that it will work fine.If anyone wants to know about how to deploy using powershell command you can refer the  techNet document for more help.

PS: if anybody who doesn't want to use either stsadm or powershell command, then i have a shortcut idea to achieve the deployment through solution gallery.

Goto central admin and deploy your solution on central admin site and then deploy on your sharepoint site. It should work. :)  

Hope this may help some one

Cheers

Pradeepa achar