Tonight, I'm in the midst of learning what should have been lesson #1 - when a new client is in the process of handing their current site over to you, NEVER DO ANYTHING TO IT UNTIL IT IS 100% ON YOUR SERVER! Even if they ask you to. Even if they just want you to change the tiniest minute detail, tell them that you can't touch it until it's on your server!
Case in point, I am in the process of transferring a new client's current site over to my server, he'll be on a monthly maintenance contract and I'll be hosting his site from now on. He asked me to change the contact form so it asked for a phone number. He wanted me to do it right away. No problem, right? I don't need to wait until the site's on my server to make such a small change, right? I have the WP admin login username and password.
So I jump into the dashboard -first thing I do is make a complete site backup and then install Gravity Forms. Find out that GF is not compatible with the 3 year version of Nivo Slider plugin that was installed. So, I update Nivo Slider - and the site explodes - White Page Of Death on the front page.
No worries, I'll just jump into the theme editor or the plugin editor and look through the code and fix the problem. I find that the admin account that I was given has super-limited capabilities. Can't access the editors through the dashboard. Ok, that's strange because it's supposed to be the admin account. But, I simply begin the restore process and my nerves are at ease. But, of course I didn't realize that the limited capabilities of the admin account would cause an error during the restore process - and the site exploded. Lost its connection to the database. Site is totally and completely gone, unable to load anything at all.
I freak out of course. I shoot an email over to the previous web guy, who had already seemed weary of giving me FTP access to the domain. I hear no answer from him. Get a call from the site owner who is fuming angry (of course, can't blame him) and I assure him that I'll just speak with the previous web admin and get access to the server to fix the issue.
End up finding out that the previous web admin knows nothing about web development and he's super busy. He is unable to respond to my pleas for server access and even if he did respond he likely doesn't know how to create a new FTP account with limited access to only the domain in question.
Whew! Here's for learning basic lessons after you've been in business for a few years!