I was trying to deploy my smart contract to the local testnet and got this error.

Error 3070003: Serialization Error Processing WASM

I was using a command cleos set contract testing . hello.wast hello.abi -p testing

Nodeos output:

  Produced block 000009736bfdf868... #2419 @ 2018-08-15T10:10:19.500 signed by eosio [trxs: 0, lib: 2418, confirmed: 0]
2018-08-15T10:10:19.780 thread-0   http_plugin.cpp:472           handle_exception     ] FC Exception encountered while processing chain.push_transaction
2018-08-15T10:10:19.780 thread-0   http_plugin.cpp:473           handle_exception     ] Exception Details: 3070003 wasm_serialization_error: Serialization Error Processing WASM
magic number: loaded 1685024040 but was expecting 1836278016
    thread-0  wasm_interface.cpp:40 validate
pending console output:
    thread-0  apply_context.cpp:61 exec_one
  • This is a very general error. Maybe you can provide some more code and explanation.
    – tmm
    Aug 15, 2018 at 11:31
  • I just used eosiocpp -o hello.wast hello.abi and eosiocpp -g hello.abi hello.cpp and just tried to deploy it by using cleos set contract.
    – JustinZ
    Aug 15, 2018 at 11:37
  • Ok. Did you try to change the folder path cleos set contract testing ./ hello.wast hello.abi -p testing? I don't know if . is a valid path.
    – tmm
    Aug 15, 2018 at 11:40
  • Yes, I have even tried to show the full path like Users/user/documents/eos/contracts/hello
    – JustinZ
    Aug 15, 2018 at 11:49
  • Are you using Docker or a local version? And did you change anything in the contract?
    – tmm
    Aug 15, 2018 at 11:55

1 Answer 1


I solved it. The problem was that I was using .wast and you can no longer use .wast you have to use .wasm

  • Cheers! Glad you solved it and answered your own question so others know how to deal with it as well.
    – tmm
    Aug 21, 2018 at 21:22
  • 1
    yeah I found it useful too(brofist)
    – NaN
    Sep 21, 2018 at 10:25

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