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Error 500

Hello I'm halfway through my uni dissertation and stumped as I can't for the life of me figure out why the designated leaf nodes can't join the master node's cluster? I'm following the documentation correctly from the ubuntu tutorial on microk8s and the official microk8s documentation page here: https://microk8s.io/docs/clustering

I can issue the add node command on the master node fine, the join command I paste into one of the leaf nodes in order to join them into the cluster to become leaf nodes.. fails with error code 500 but isn't helpful. Could anyone point me in the right direction? I'm using Ubuntu server for ARM.

I am using carrier grade NAT, a 4G router with a 4G simcard inside; could this be the cause of the problem? Thanks for your time.

115MPH
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4 Answers4

1

I had the issue of not being able to join the cluster as well. It appears to be a permissions problem. I solved the issue by using:

sudo microk8s add-node (on the master. I know you are supposed to be able to just use microk8s add-node)

sudo microk8s join \<ip address of master\>:\<port\>/\<token issued by master\> (on the joining node. Once more you are supposed to be able to just use microk8s..., but it does not work)

version is microk8s classic 120.2

karel
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Courtney
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This is a recently reported bug, see Microk8s issue #2016. A fix is expected soon, if not already pushed as a snap update.

Nikkoura
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I have been keeping up to date but I was under time constraints, I installed k3s instead as a solution. Thanks for getting back to me, I appreciate it! nodes successfully joined without issues

115MPH
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As July 2025 and MicroK8s v1.32.3 revision 8148 for each node to be added into the cluster it is necessary to run:

microk8s add-node

and at the needed node run the respective

microk8s join ....

generated command.

Also, just in case I opened the port 25000/tcp and 25000/udp. (should I keep these rules?)

The use of sudo was not needed since I used:

sudo usermod -a -G microk8s <YOUR USERNAME>
sudo chown -R <YOUR USERNAME> ~/.kube

This is different to kubeadm or k3s where a common token is used to add a node

Jose Cabrera Zuniga
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