It is impossible to help without said error message. Though honestly, if it's just Omnir's mods you're using, I would suggest giving him the errors as the problem is most likely in them. If he never rebuilt his mods for R16 though, it's likely you just need to rebuild them yourself.
I've already been there. He said 2 check here. Here is the errors copy and pasted from the thread:
When I open the game i get this:
>>> Singleplayer: 22:19:02 <<<
TAPI.Mods+LoadException: OmnirsNosPak.tapi: System.TypeLoadException: Could not load type 'TAPI.ModBuff' from assembly 'tAPI, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.
at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type)
at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase)
at System.Reflection.Assembly.GetType(String name)
at TAPI.ModJsonHandler.HandleBuff(ModBase modBase, JsonData j, String fname) in x:\tAPI Core\tAPI\Mod\ModJsonHandler.cs:line 1447
at TAPI.ModJsonHandler.Handle(ModBase modBase) in x:\tAPI Core\tAPI\Mod\ModJsonHandler.cs:line 59
at TAPI.Mod.<Load>b__0(BinBuffer bb) in x:\tAPI Core\tAPI\Mod\Mod.cs:line 276
at TAPI.Mods.HandleTapiModFile(FPath path, Action`1 action) in x:\tAPI Core\tAPI\Mod\Mods.cs:line 449
at TAPI.Mods.HandleModFile(FPath path, Action`1 action) in x:\tAPI Core\tAPI\Mod\Mods.cs:line 427
at TAPI.Mod.Load() in x:\tAPI Core\tAPI\Mod\Mod.cs:line 107
at TAPI.Mods.Load() in x:\tAPI Core\tAPI\Mod\Mods.cs:line 539
at Mods.Load()
Mods used:
OmnirsNosPak (Omnirs Nostalgia Pack 1.0.4.3 by Omnir)
BaseMod (Grox The Great's BaseMod 1.0.5 by Grox The Great)
And when I try to play i get this:
>>> Singleplayer: 22:17:17 <<<
System.NullReferenceException: Object reference not set to an instance of an object.
at TileDef.GetCodeHandler(Int32 type)
at TileDef.GetCodeHandler(Int32 x, Int32 y, Boolean wallCode = False)
at Lighting.PreRenderPhase()
at Lighting.LightTiles(Int32 firstX, Int32 lastX, Int32 firstY, Int32 lastY)
at Main.Draw(GameTime gameTime)
Mods used:
OmnirsNosPak (Omnirs Nostalgia Pack 1.0.4.3 by Omnir)
BaseMod (Grox The Great's BaseMod 1.0.5 by Grox The Great)