- Make sure you meet all the minimum requirements for the version you're running. For EDK3, these can be found here.
- Although it's not actually mentioned on that page (it is in the installer though), you need PHP's safe_mode setting turned OFF.
- Try clearing your cache first.
- If you have error messages like 'unable to write to cache/whatever', chmod the /cache folder to 777 via your FTP client or hosting control panel.
- If you get something like 'Fatal error: Smarty error: unable to write to $compile_dir '/path/to/kb/install/templates_c', chmod /install/templates_c to 777.
- If you have a '500 Internal Server Error' and nothing else displayed, look at your error logs and post the last few lines.
- If the error mentions a missing file, try reuploading everything to be sure nothing got missed out.
- Search the forums, a solution to your problem may already be posted.
If I think of anything else I'll update this post.