nether494 the following extensions are holding you back:
fof/links 0.3.0 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)
fof/sitemap 0.5.3 requires flarum/core (>=0.1.0-beta.13 <0.1.0-beta.14)
fof/stopforumspam 0.2.2 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)
fof/upload 0.10.1 requires flarum/core (>=0.1.0-beta.12 <0.1.0-beta.14)
I have not checked whether all of them have beta 15 compatibility. If they do, you could try replacing their version constraints in composer.json
with *
. The Extiverse helper can help you do that if needed https://discuss.flarum.org/d/25246-extiverse-helper