1. Install a new Liferay.
2. Click on Portal Settings -> Display Settings
3. See what is in the Default Regular Theme's list. You see only: "Classic".
4. Don't change anything, just click on Save button.
5. Check again the Default Regular Theme's list. You will see 2 items: "Classic" and "classic,mobile(Undeployed)"
6. You can't change to "Classic", because if you try, and then click on Save, it will "classic,mobile(Undeployed)" again. (I made an issue about it earlier:
7. Click on Sites. Create a new Blank Site.
8. Click on Site Pages (in the content section you see the site you just created). You see, the Current Theme is "Mobile". And there is no any other option.
9. Click on Add page. Fill the Name, and then click on the Add page.
10. Click on the newly created page in Go to menu.
At this point an error message appears on the screen: "An unexpected system error occurred
javax.servlet.jsp.JspException: com.liferay.portal.kernel.template.TemplateException: Unable to process template SERVLET_CONTEXT/wap/themes/mobile/templates/portal_normal.vm ". The errors in the log is attached.
If you skip the 2-6 steps, everything is OK.