Old page have a lot of extras and I'm afraid it will not work in 2.4.0I believe that requires more careful evalution...what extras exactly? Do you convinced there are no updates/compability fixes for all you extras? I think you have to check for each one separately.
It would be okay if I copy table from database "modx_site_content" to new database?Only this is not enough, you can break something and generally speaking this is dangerous way. Please use more traditional way:
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There is a new extra for upgrading that is very good, it's called UpgradeMODX. http://modx.com/extras/package/upgrademodxThanks a lot, Susan! I don't know before about that Bob's useful solution, will check it shortly.