If you look at the IBlockState class do you see a method called getPropertyKeys, or is it called getPropertyNames?
The method was renamed from getPropertyNames to getPropertyKeys on 2016-11-17. If you see the old name, you should update your MCP mappings to stable_29 (the final mappings version for 1.10.2).
If you're using an obfuscated build of EnderIO, it should be automatically deobfuscated to your current MCP mappings. This error suggests that you're using a deobfuscated build or EnderIO/EnderCore are messing with the deobfuscation.