According to gaminggeek.dev on the Minecraft discord, this is caused by the new certificate on sessionserver.mojang.com who’s CA isn’t included in the JRE versions shipped by the official launcher. Downloading the latest java 8 version from https://adoptium.net/temurin/releases?version=8 and selecting it in the launcher solved the issue for many users.
Would updating the java 8 version used in the official launcher be an option?
Sending the parameters as an array should look like this:
{
"jsonrpc":"2.0",
"id":3,
"method":"minecraft:players/kick",
"params":[[{
"player": {
"name": "PetergrineFalcon"
},
"message": {
"literal": "You have been kicked."
}
}]]
}
This is correctly accepted by the server. You had an extra object in there, that isn’t correct.
Still present on 1.21.9-pre3
The issue continues to occur on 1.21.9-pre2.
Issue still exists on 1.21.9-pre1
Issue persists on 25w37a
Sorry, my bad: the allowlist one is also fixed
This issue still occurs with the minecraft:allowlist/clear
method. Only the other methods have been fixed.
Did you update java on both your client and the server? Are you sure you selected the correct java installation in the launcher?