Restart Hearthstone and HDT.
If the problem persists: See here on how to manually set up the log.config.
Problem still persists: Make sure the Hearthstone path is set correctly. options > tracker > settings > set hearthstone path (There were user reports of this not working, to manually do this: Close HDT, go to
%AppData%/HearthstoneDeckTracker(Win+R, paste), open the
config.xmlwith any texteditor and look for <HearthstoneDirectory>...</HearthstoneDirectory>. Set this to the correct path.The correct path is the one used in the Battle.net app options (Battle.net icon > Settings > Game Install/Update > Game Installation > Hearthstone)
Check if the log files are created at <HearthstoneDir>\Logs and written to. If there aren't any logs or if the logs are outdated:Unblock Hearthstone in your antivirus programs
Exit Hearthstone, delete
%LOCALAPPDATA%\Blizzard\Hearthstone,start HDT and then start Hearthstone again
If you are using the same Hearthstone installation since beta, try reinstalling Hearthstone (see here)
Here's how to fix this problem.
Written by Andrew BrownUpdated over a week ago