In Configuration > Logfile you'll find an overview of all in the backend done actions:
The table shows you every backend useraction like saving an article or the message of an error you got in the backend with date, user, module, message and the options (3) you can use to delete or open a message. If you want to delete multiple messages, select the messages you want to delete and click delete marked entires (1). Per page you see 20 entries, using the pager (4) you can change the pages. By searching (2) for users for example you can seperate all messages by the desired user.
You can also see the messages of the system log in backend. You will find the new tab called "System log" (1) at Configuration > Logfile. Clicking on the magnifying glass (2) gives detailed information about the individual messages. In the "File" area (3) you can switch between the individual log files and also download log files, if you want to forward them, for example.
Around Shopware there are different places, where errors can occur, which the module can't log. How to debug this, we'll show you here.
The cronjob "CronRefresh" deletes all entries, which are older than 30 days. More information can be found here.