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.