SharePoint Destination

Can I restore SharePoint 2010 Site Collection backup into SharePoint 2013 environment? No, it won't work that way. You should do a backup and restore in your SP 2010 environment and put the site collection into it's own database. Then do a sql backup and restore of the database into the 2013 farm and content db attach it for it to upgrade correctly

http://blogs.technet.com/b/meamcs/archive/2013/02/24/sharepoint-provider-hosted-app-walkthrough-part-1-preparation.aspx  

Issue   All of a sudden, when your BCS stopped working and you are getting the below issue, "Cannot connect to LOB system"   Cause of the Issue   BCS files may be referring the wrong connection wrong and you might have changed it in the bcs files. Also BCS files would have been updated in the SharePoint server, but still you are getting the issue.   Resolution Issue is old files are not properly updated and still referring the old connection string. So you need to delete all the BCS files and again need to deploy it in the SharePoint server. This solves the issue.