I am fast syncing geth, and at block 4080496 it started to sync very slow. Those 4 million blocks took about 45 minutes to sync.

In the last 4.5 hours I have got to 4081691, about 1200 in 4.5 hours.

Other people on my team got stuck around the same number. Is there any specific reason for this happening?

  • 1
    Hi there. Which network are you syncing to? The mainnet, or one of the testnets? Commented Sep 21, 2018 at 8:58
  • syncing to mainnet Commented Sep 21, 2018 at 11:16

2 Answers 2


Ah, so I realize now I am connected to the testnet. I did not give the chain ID to geth, so then it must have picked up ropsten, and went with that. Always make sure you are on the right chain!


It sounds like you are doing a fast sync. In this mode, you download the block headers, the block bodies, it processes no transactions until current block. Then it gets a snapshot state and goes like a full synchronization.

Final syncing of the last ~200 blocks does not complete until all states have been synced. At the end the blocks stop downloading only the states sync until they completely catch up then syncing of the blocks will finish. Depending on your system it can be stuck on the last ~200 blocks for several hours.

  • 1
    Almost definitely a fast sync, no way a full sync can do 4.5m in 45 minutes, the spam attack in the ~2m block range will take a few hours alone Commented Sep 21, 2018 at 14:47
  • 1
    You are correct. I will edit my answer. Commented Sep 21, 2018 at 14:47
  • yeah but I am still processing like 5 blocks a minute at around 4,085,000. And the mainnet is at ~ 6,700,000. It is not in the ~200 range yet Commented Sep 22, 2018 at 0:13

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