Command blocks let you run commands automatically with redstone or a click. Servers have them switched off by default, so you need to enable them first.

Newer versions (1.21.11 and up)

Newer versions use a gamerule instead of a setting in the properties file.

1. Open your server in the panel  and go to the Console tab.
2. Run the command for your edition:
   • Java: gamerule command_blocks_work true
   • Bedrock: gamerule commandblocksenabled true
3. To turn them off again, run the same command with false.

You can also run it in-game as an operator by adding a / in front. If you use Multiverse or a similar world plugin, gamerules may need to be set per world.

Older versions (1.21.4 and below)

1. Stop the server and open the Files tab.
2. Open server.properties.
3. Find enable-command-block and set it to true.
4. Save the file and start the server again.

To make yourself an operator first, see Make Yourself an Operator.