Whenever I attempt to run geth on the command line, it seems to have trouble syncing with the blockchain. I am absolutely a novice so I could be completely overlooking. I am getting these warnings continuously(This is run on testnet):

WARN [04-21|17:40:40] Ancestor below allowance                 peer=20c9ad97c081d633 number=647267 hash=000000…000000 allowance=647267
WARN [04-21|17:40:40] Synchronisation failed, dropping peer    peer=20c9ad97c081d633 err="retrieved ancestor is invalid"

Please let me know if there is a solution for this. Thank you!

  • 1
    It's also important to note that this is on the testnet Apr 21 '17 at 22:24
  • Which version of Geth are you running? How many peers do you see in the output of admin.peers()? (Don't really have any ideas on this... ) Apr 24 '17 at 20:35
  • 1.5.9 and where do I enter that command? The geth console? If so, I'm getting a 'peers' is not a function error Apr 24 '17 at 22:37
  • I'm having exactly the same issue using geth v1.6.1-stable-021c3c28, deployed on Ubuntu on Microsoft Azure. Testnet, same as OP. May 9 '17 at 7:18
  • In my case it happend because very old synchronization run long time ago. If it is your case, just delete all *.ldb files from ~/.ethereum/testnet/chaindata/ directory. Hope it will help. May 21 '17 at 2:41

I received this error as well.

I deleted everything in the folder /Users/name/Library/Ethereum/testnet/geth/chaindata and then restarted with the command geth --testnet --fast and it started working


Ethereum testnet has different versions, now the main testnet is called Ropsten. you can see all of the ongoing Ethereum testnets here: testnet.etherscan.io

It should be noted that Ropsten testnet was attacked in Feb/March 2017, which lead to a fork on the testnet to revive the network. More to read here: Ropsten Revival

To use the revived version, you need to remove the database and start resyncing using the revived nodes: Ropsten testnet PoW chain


I did the following:

➜ ~ rm -rf ~/Library/Ethereum/testnet/geth/chaindata


➜ ~ geth --testnet --syncmode "fast" --rpc --rpcapi db,eth,net,web3,personal --cache=1024 --rpcport 8545 --rpcaddr --rpccorsdomain "*"

And it should works


I had this problem, where my chain was just perpetually ~90 blocks away from current. Restarting geth fixed it for me, luckily.

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