So what I do then is go through the process of upgrading it up to 3.4.5. I've then been restoring the website onto the test domain. Basically I use Akeeba to back the website up.
So what I've been doing is using a couple of spare domains to practice. I have two websites left to do, these are the two websites that are most important to me and therefore I need the whole process to go without any problems and as quickly as possible. I have slowly been updating all my 2.5 websites up to the latest version. For some very annoying reason I started getting this problem today.