will I have problems, if I change a user name on a small forum. it runs on vbulletin. the user has 2000 posts. I read this and so am not sure if I should.
Do a backup first (just in case), then go for it... As Doctor Love said, it's been done many times. At worst, you'd just need to put the back up in, though in most cases, it's a rather smooth change.
I Have Done a Change on a large forum and at least for me, there was No problem and it was a smooth change. Bus yes, Take a latest backup as a precaution.since the site is big, you will usually have a regular backup but you wont want to lose posts, threads so take a latest backup and then try this change.