Be sure to use <a href="https://notepad-plus-plus.org/" target="_blank" rel="noopener noreferrer">Notepad ++</a> to open them, other editors are available, such as: <a href="https://www.sublimetext.com/" target="_blank" rel="noopener noreferrer">Sublime</a>, <a href="https://atom.io/" target="_blank" rel="noopener noreferrer">Atom</a>, <a href="https://en.wikipedia.org/wiki/TextEdit" target="_blank" rel="noopener noreferrer">Textedit</a>, <a href="http://www.barebones.com/products/TextWrangler/" target="_blank" rel="noopener noreferrer">TextWrangler</a>, <a href="https://www.baremetalsoft.com/baretail/" target="_blank" rel="noopener noreferrer">Baretail</a>.You can increase the size of the logs via the Admin UI under Options / Advanced, if it is a busy site and a rare issue this is well worth doing so the problem is captured in the logs and not rotated out</div>