In theory, there is no limit. Your host, however, can limit the resources available to generate links. This thread might provide you some options: http://wordpress.org/support/topic/the-menu-has-a-limit-of-49-links-of-pages-in-the-navbar
Thread Starter
strofe
(@strofe)
I tried to put all the pages I wanted off the top menu in another menu, but it didn’t work. Contacting my host, HostGator, they found out that a limit indeed had been reached for the “max_input_vars” setting for this package’s PHP scripts, and they increased it from 1000 to 5000. So, now it functions, and I am happy!
Thread Starter
strofe
(@strofe)
I’m continuing this thread, because now I have a similar problem. I’m using the “Hide Pages” plug-in by Peter Coughlin, which allows me to hide pages from the Top Menu. I have now reached 1,275 pages on my website, and new pages that I am adding aren’t turning up neither on the Top Menu nor in the “Hide Pages” register. It seems to me that I have reached a new limit somewhere. I need to add a few hundred pages more and would be happy if someone was able to fix this problem.