Yes I know as in old mods etc that use deprecated values etc and yes someone was upgraded to 4.2.2 and to php5.4 then had to move them back to 5.3.27 I believe and it worked fine (yeah 4.2.2 on 5.3.27 but then on another 4.2.2 site it would not function properly on 5.3.27 but it was new the owner said forget it Mike just install me 4.2.1 so he could get going with the site as it was brand new but not everyone can simply do that i.e. if their forum has been long standing and has thousands of threads and posts etc) long story short every site there's been an issue on was custom regarding modifications/plugins so in essence unless you do a test server/site (most host will accommodate that request for free if you call and explain what is going on to them, if not perhaps a nominal fee and you will more than likely need to edit your hosts file to view the new site on the different server IP) then you just don't know and that compatibility tab in the admincp does not work all the time, it's a band-aid per say you should do as the hint suggest and sort the issues properly.

I'm not recommending 4.2.2 at all now, same as vB5.x I suggest 4.2.1 but that's because of the mod issues as some owners simply don't want to deal with all that, had them tell me that on the phone despite me telling them 4.2.2 and 5.4 will ensure their site runs smoother for longer (if no issues).

Thats good advice,but it's not only down to mods/plugins.Vb is also different on specific php versions,but we cant go constantly testing php versions with the vb version or the mod/plugin.So we really need to see some more system requirements being more specific as to the version of 5.3 or 5.4.

LOL, just to add to the confusion...

4.2.2 is running fine on PHP 5.3.10 for me. :D

Now on vBulletin 3.8.9 Beta 2, but still looking.

Threads: 127,761, Posts: 1,041,312, Members: 74,459

If it ain't broke, don't fix it.

vB5.1 is broken, do NOT use it under any circumstances on a site you care about.

I suppose it could be considered broke in that I'm finding mods for version 4 that I cannot run on version 3.

If I update to 4, what exact version should I be targeting toward for starters?

Looks like Paul says: 4.2.1 or 4.2.2

My suggestion is to stay far far away from vbulletin 5. It's nowhere near ready for prime time.
vBulletin 5 is broke in the fact that most of the site does not work and your members will hate you for "upgrading" to it.

4.2.3 (wait for Beta 3 now, its due out soon).

For vB3, 3.8.9 (again, Beta 3 due in a week or two).

You should list them. BoP5 has a huge list of v3 mods that work in v4, and otherwise. The two platforms are not so dissimilar that v4 mods cannot be also coded/ported to v3.

That's not a definition of "broken" by the way. You'll see "broken" and alot of misery and heartbreak - and loss of a ton of regular users - on a botched or glitchy "upgrade."

I've seen this happen even with a smooth "upgrade."

What's the compelling reason to "upgrade?"