I have not changed anything in my code that used to run without this error. The transactions, once approved, still work fine.

The warning I get from phantom wallet is:

Unable to simulate. Make sure you trust this website since approving can lead to loss of funds.

I tried this both with a transaction that involves my custom program, as well as with a transaction that is just SystemProgram.transfer(). Both give me this warning.

I have also tested with this site on devnet: https://solana-twitter.netlify.app/#/ which was not written by me, and in the past it did not give me a warning, yet now it does.

Is there any way to get rid of this warning? If you need more information please let me know.

2 Answers 2


This is a bug that arose from a recent update to our mainnet simualtors. We should have testnet/devnet simulators working soon!

  • are you guys also familiar with tokens not being recognised bug ? solana.stackexchange.com/questions/2387/… there is also a problem where it's not showing how much is being transfered, you have to click "advanced" tab to see the amount of funds being transfered.. like it's very buggy..
    – sensei
    Commented Aug 24, 2022 at 12:27
  • It's been almost a month, and this bug looks like it is here to stay.
    – Qpqpqpqp
    Commented Sep 15, 2022 at 20:17
  • Testnet & Devnet should now be simulating correctly along with Mainnet. We have some additional work to do to simulate properly on Localnet. Commented Sep 22, 2022 at 23:08

I think this is just an issue with phantom wallet on devnet - this is always the case for me as well. This is pure speculation but I suspect this is because phantom wallet run the transaction simulation through their own RPC servers which are connected to mainnet-beta only

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