Upgrading CI generates error

[eluser]TheFuzzy0ne[/eluser]
Why do you need to upgrade? What are you missing out on?

[eluser]Computerzworld[/eluser]
Actually I am facing some other problems too in older version like when I send mail using older version(1.6.1), attachment won't goes. While it is going with attachment if I upgrade the version to (1.7.1). Also I am facing several DOMPDF releated issues in the older version. That's why I need to upgrade it.

[eluser]TheFuzzy0ne[/eluser]
I've already explained that there are some differences between the two versions' database Active Record classes. With this in mind, it should be very easy for you to upgrade your code to work with the current version. If you can't, the post you're problematic queries, and I'm quite sure someone will take a look at it for you.

[eluser]Computerzworld[/eluser]
currently I have not upgraded the database files and they are in old version only and it runs fine. The main reason behind asking for this question was to know if in anyway the upgraded version works fine or not. Anyways thanks for your kind support.