JSON - "Exception in server tick loop"

Category Common Errors Last updated Oct 4, 2026 2 min read

If your server doesn’t start and shows an error similar to the one below, it’s usually caused by a corrupted or malformed ops.json or whitelist.json file:

java.lang.NullPointerException: Exception in server tick loop
at net.minecraft.server.v1_7_R3.JsonList.load(JsonList.java:171)

The exact class name in your error (v1_7_R3 above) will vary depending on your server version and software, but the key part to look for is JsonList.load, that’s what tells you this is a player-list file problem, not something else.

Why This Happens

ops.json, whitelist.json, and banned-players.json are all stored in the same JSON-based format on your server. If one of these files becomes corrupted, for example from a crash while it was being written, a bad manual edit, or a failed import or restore, the server fails to parse it when loading at startup. Since this happens very early in the boot process, it crashes the entire server before it can even finish starting.

How to Fix the “Exception in Server Tick Loop” Error

Stop your server from the Console page.
Go to File Manager.
Delete the following files:
- ops.json
- whitelist.json
- usercache.json
Start your server.

Your server should now boot normally. These files will be recreated automatically as empty files once the server starts.

After Fixing It

Deleting these files clears your operator list, your whitelist, and your username cache, they don’t come back on their own, so you’ll need to set them up again:

Re-add your operators using op <username> for each player who had operator status.
Re-add your whitelist using whitelist add <username> for each player, if you had whitelisting enabled.
The usercache.json file will rebuild itself automatically as players join, no action needed there.

If you keep running into this same error repeatedly after fixing it, it may be worth checking what’s causing the file to become corrupted in the first place, such as an unexpected crash or a plugin that’s writing to these files incorrectly. If you’re not sure, contact support with your server ID and we can help you investigate.