Bitcoin Cash sendrawtransaction error?
It looks like the error message for receiving a legacy transaction on a Bitcoin ABC node: https://github.com/Bitcoin-ABC/bitcoin-abc/blob/174846aaaf564e64b6bd06d679996b52ba86ad53/src/validation.cpp#L1445

Speculation:
It seems plausible that Bitcoin ABC would create regular transactions before reaching the fork in order to retain compatibility with the Bitcoin network, but then recognizes them as being invalid to the upgraded network. (This is unverified speculation.)