If you’re experiencing issues during theme installing or importing demo data via setup wizard and you see message like that: “Are you sure you want to do this? Please try again” please make sure that your PHP configuration is set at least as below:

max_input_time = 300
max_execution_time = 300
memory_limit = 258M
upload_max_filesize = 256M
post_max_size = 257M

Here’s a list of possible WordPress errors, including HTTP errors, database errors, and other common issues when your PHP/server settings are too low.

Error 500 - Internal Server Error
Error 403 - Forbidden
Error 404 - Page Not Found
Error 401 - Unauthorized
Error 400 - Bad Request
Error 502 - Bad Gateway
Error 503 - Service Unavailable
Error 504 - Gateway Timeout
Error Establishing a Database Connection
White Screen of Death (WSOD)
Maximum Execution Time Exceeded
Memory Exhausted Error
429 Too Many Requests
Connection Timed Out
Destination Folder Already Exists