Upgradable smart contract cannot be upgraded "contract is not upgradeable"


I'm trying to deploy a upgradable contract to Defender by following this tutorial: https://docs.openzeppelin.com/defender/guide-upgrades

Unfortunately after I propose the upgrade click "approve and execute" it just returns "Contract is not upgradeable"

I am using Polygon Mumbai network and the smart contract code I am using is the Box code from the example

I'm really not sure what I'm missing and would love if someone had any ideas for what might be happening... I've also attached a screenshot in the hopes that someone can maybe see something useful

Hi Ben, in the past we've seen this behaviour with certain Polygon providers, who can't respond to eth_getStorageAt properly.

I'd suggest that you tried configuring your MetaMask connection to Mumbai to use some other provider. We usually get the best results with Infura and Alchemy. Try to avoid the public endpoints if you are looking for higher reliability.

As a side note, we're working on a couple of enhancements to make Defender more robust to these kinds of issues, but those won't be live until at least next week.

thanks so much Martin

I changed my metamask RPC URL to use my Alchemy URL (as per this guide and it now seems to be working perfectly!