The error logs will help you in resolving issues such as blank pages when diagnosing issues with your website. Below are the steps to check website error logs.
1) Log into Plesk panel. Then click on Website & Domains tab > then click on Show More.
2) Next click on Logs.
3) By default all logs will be displayed i.e. access and error logs included on the same page.
4) From the Drop Down on the right, you can select only the logs you want to be displayed
e.g. Apache error to assist in resolving an issue with the website.
5) Plesk 12.5 has the included functionality of Real Time logging. Click on Start real-time updates.
6) Click on Clear to remove previous logs from displaying. Reload the website to view real-time logging