Trying to build for Facebook Gamesroom and getting this error:
Extension Library/FacebookSDK/Facebook.unity.gameroom.dll was not registered, that means it relies on default unityextensions settings, please register extension and apply necessary settings for it in the callback
um … yeah, say what? No idea what this is on about and nothing much turning up in searches, I would assume this stuff should just work rather than require me to go off registering extensions etc?
Im also having the same issue on my side, I installed the Facebook build support add-on and I do have GameRoom installed as well and my platform switched to facebook but the build settings windows says “No PC, Mac or Linux Standalone Module loaded.” on the Facebook build settings with a Open Download Page button that leads to a 404:
Please if anyone can shed some help or advice on the matter it would be greatly appreciated.
It also seems to have completely messed up my Standalone PC, Mac and Linux build option as it only displays the tick boxes for “Development Build”, “Autoconnect Profiler” and “Script Debugging”. The Facebook Build Platform seems to completely mess up my Standalone build support. Which is weird as PC Standalone support is built into the Windows version of Unity.
Im running on Windows 10, and using Unity 5.6.1p1
Ok, it seems I was able to solve this by upgrading to Unity 5.6.2p4.
Although it only played once. I cant get it to play again, it builds just fine but then just never plays it.
I am building on both Win10 & Win7 x64 environments on multiple real & virtual boxes - I had same issue on v2017.1, 2017.2beta, and even after backlevelling to 5.6.2p4.
I could initially build a facebook target .exe, but any subsequent attempt to build for other targets had numerous facebook & gameroom.dll registration errors preventing build completion.
Even after deleting facebook SDK, reimports kept recreating the SDK folders.
Completely deleting the Unity program installation subdirectory \Editor\Data\PlaybackEngines\Facebook, let me build for standalone again, but still some issues remained.
I was only able to work around it by having two completely separate Unity installations, one WITH facebook build support, and one without.
I had to use a Version Control System like SVN to commit my original assets & related data from the original project subdirectories, and check them out to a new separate subdirectory for use with the other Unity installation.
Now the initial error as mentioned still appears, but it is not preventing .exe builds, and I can get the Facebook Gameroom to open and run the built .exe no probs.
Hint - if your Facebook Gameroom is not starting up, (or at least not starting with your built .exe),
first check that Facebook Gameroom starts and shuts down ok in Windows outside of Unity.
It could be caused by the automatic upgrade Facebook Gameroom does after installation, which sometimes leaves two conflicting versions installed (in which case, uninstall the old version and restart windows)
It could also simply be caused by Facebook Gameroom not cleanly completing its autorun at windows startup, in which case, usually a windows restart gets it working again - if not, uninstall/reinstall FBGameroom.
It is usually a good idea to start up a Facebook Gameroom window before you start Unity, to eliminate that as a factor when doing your facebook target build.
Finally, if FBGameroom is starting ok, but Unity is not kicking off a successfully built FB target .exe inside FBGameroom, you should have the option within your Facebook Gameroom account dropdown menu, to run a [DEV] Debug Local Unity Game build, which either opens a file choice dialog for you to pick the built .exe, or it takes the most recent chosen built .exe and run it.
As of today, I find that the security patch for Unity means yet another mass download of a new version which I’ll have to roll out over all my multiple build machines, real & virtual 
Awesome, thanks so much for the advice. I think Ill wait a teensy bit on Facebook right now and finish up my Windows Store game first before I come back to it. Thanks again for the adivice, appreciate it
No worries, very happy if it helped you or anyone else You have my admiration in turn for your pursuit of a Windows Store / UWP build - that little holy grail remains out of my reach for now, due to unexplained Unity & signing & other various errors even on W10 Creators Edition + latest Microsoft UWP SDK… meh… 
Yeah Windows Store/UWP does seem to b a very tough cookie to crack, Im making headway bit by bit. Not sure if Ill be of any help as we are using the ID@Xbox route not the W10 Creators Club route and we are signed under NDA to not share confidential info outside of approved methods/forums.
We’ve needed to switch over to IL2CPP and get some help from the Xbox One forums in order to get stuff working and we are currently waiting on a new Unity patch update that would fix a big bug for Windows Store, so yeah I feel your pain, I think its been the toughest platform that we’ve taken on yet.
Say no more, NDAs are everywhere now, SteamWorks/Direct, Facebook Gameroom, Google Dev Play Store, etc - because after all, they’re doing us a big favour allowing us to give them 30% off the top
That notwithstanding, my hat remains tipped to your team’s gallant efforts, and I wish u the best… Yes, IL2CPP Unity errors were one of the many issues I had awaiting a Unity patch to address…
I copied the dll files of facebook in unity folder to system32 folder, now its not showing any errors, hope this doesn’t give me problems in future.