This article will guide you on how to fix #drupal unexpected error. Drupal error occurs due to many reasons that include corrupt #database, non-compatible modules installation, cache, #PHP configuration, custom codes, and so on.
1. An "Internal Server Error" is an #error on the web server that you're trying to access. 2. That server is misconfigured in some way that is preventing it from responding properly to what you're asking for.
3. An "Internal Server Error" often occurs due to: Misconfigured Drupal core file or folder read and write permissions.
To clear cache in #Drupal:
i. In the Manage administrative menu, navigate to Configuration > Development > Performance (admin/config/development/performance).
ii. Click Clear all caches.
iii. A message saying the cache has been cleared appears at the top of the page.