It happens after you have just edit the store setting.
After you setting the store, and you go back the front end, you find that your website can’t connect all the information page.
It may because of you have just change store setting >> server >> Use SEO urls to “Yes”
Simply, change to “No”, then the problem is solved.
if you want to use SEO url, and change this setting to “Yes”, you should also upload the .htaccess file to your website.
When you extract the opencart package, you will find a file “.htaccess.txt”, please rename it to “.htaccess” and upload to your website.
Done