INVALID_KEY

One of the keys used in this transaction is not valid.

[Error Code: 1006] invalid proposal key: public key 0 on account 50ea7bc3f8e5d899 does not have a valid signature: [Error Code: 1008] invalid payload signature: public key 0 on account 50ea7bc3f8e5d899 does not have a valid signature: signature is not va