Update: I tried to generate an empty block but failed. Why still need fee?
2112038ms th_a db_block.cpp:195 _push_block ] Failed to push new block: [114/1936]
3030007 insufficient_fee: insufficient fee
Insufficient Fee Paid
{"core_fee_paid":0,"required":10000}
th_a evaluator.hpp:230 evaluate
{}
th_a evaluator.cpp:46 start_evaluate
{}
th_a db_block.cpp:653 apply_operation
{"next_block.block_num()":3067959}
th_a db_block.cpp:536 _apply_block
2112038ms th_a witness.cpp:178 block_production_loo ] Got exception while generating block:
3030007 insufficient_fee: insufficient fee
Insufficient Fee Paid
{"core_fee_paid":0,"required":10000}
th_a evaluator.hpp:230 evaluate
{}
th_a evaluator.cpp:46 start_evaluate
{}
th_a db_block.cpp:653 apply_operation
{"next_block.block_num()":3067959}
th_a db_block.cpp:536 _apply_block
{"new_block":{"previous":"002ed036dea60c5872751faccc904c4c04d8edc0","timestamp":"2016-01-29T00:35:12","witness":"1.6.35","transact
ion_merkle_root":"0000000000000000000000000000000000000000","extensions":[],"witness_signature":"1f2eb9e040001a6aee45bdf4dbc0845c00d91
b0418cd5eaa577643a8b72bc7f73838f904a2dc23d40dc8a36f224b5c63205200f9ade4d195baed079d9ec14375a9","transactions":[]}}
th_a db_block.cpp:201 _push_block
{"witness_id":"1.6.35"}
th_a db_block.cpp:405 _generate_block