Monero log error messages ("transaction extra has unsupported format")

Question

I'm using the Linux Monero command line client v0.11.1.0 compiled at home from github with no errors at all and I can find in the wallet log file many error messages like this:

WARN    wallet.wallet2  src/wallet/wallet2.cpp:660  Transaction extra has unsupported format <too_long_to_copy_string...>

I have the same errors messages when using a Monero client compiled by monero devs found on github.

Every time I open my wallet, the monero wallet writes in the log file many of these error messages. I have two questions. 1) is it a problem ? 2) I'm waiting for some mining pool payouts and I want to know if these error messages are related to some payments sent to me that have been rejected, what can I do in this case ? Many thanks in advance for your replies.

Answer 1

This error happens when the extra field in a Monero transaction cannot be fully parsed. This may or may not be a fatal error: the transaction public key (which is needed to scan for incoming monero) is located in that field, but is usually present before such errors.

One recent cause for these errors is a slight issue in subaddress code recently pushed to master, which would add an empty list of additional tx keys where none was needed (this has since been changed). It seems likely that the transactions showing that error are sent by people using Monero software built from master with that issue.

In any case, if this is indeed what is happening, the message can be ignored as the tx public key is already extracted and scanning will proceed normally.