Bump. It wasn't a client add-on. I checked all my recent add-ons. I really need help here!
I'm not so sure you're disabling the client add-ons or server add-ons. follow my steps exactly.
Delete all add-ons or goto your add-ons folder, move it somewhere else or rename it. If using steam goto step 1, if using non steam goto step 2:
Step 1:
>>Right click on blockland in your library
>>Click on properties
>>Click on local files along the top in the window that pops up
>>Click on verify local content or something similar
>>Steam will download any missing stuff (Including a fresh new add-ons folder)
Step 2:
>>Launch blockland
>>Blockland will redownload the files through the launcher
Launch the game and if the game works, then it is an add-on or client mod doing it, if it still doesn't work, move the add-on folder back or rename it back to it's original name.