How to fix SyncMate kernel panic at El Capitan boot

Solution 1:

So, for anyone who is in a similar position to me, the critical step that I was missing after getting rid of the offending .kext, was removing the various caches that were resulting in it still getting loaded during the FileVault startup process.

Removing /var/vm/sleep* and /var/folders/* from the FileVault volume caused all the caches to be rebuilt and the system booted correctly.

Solution 2:

When you say the Mac doesn't boot - can you get it booted in safe mode (holding shift)? If so, you can delete the kext and try again a normal boot.

Worst case, you could boot into Recovery HD and open terminal from the utilities menu. Delete the offending kernel extension and then try booting again.