Yes searching is easy, just type some words like "haproxy 2.3 error" produces exactly 10 results for me, several having more or less the same information about removing old files. Or if you search for "haproxy 2.3" the very first result is a "Installation and Upgrades / HEADS UP on 2.3 upgrade if using haproxy".
Anyway if your still having issues after trying the removal of old files, please do post the error messages you experience and maybe some advice specific to your installation can be provided.
Regards,
PiBa-NL