I have been setting up MainWP on Windows and I ran into an issue when trying to add my first site. MainWP’s dashboard gave me an error, “Invalid Request” – not very descriptive. When I looked in my PHP error log I found: “[10-Dec-2016 14:20:34 UTC] PHP Warning: openssl_pkey_get_details() expects parameter 1 to be resource, boolean given in [PATH_TO_SITE]\wp-content\plugins\mainwp\view\view-mainwp-manage-sites-view.php on line 1737
A bit of Googling told me that MainWP looks for OpenSSL, and if it doesn’t exist it falls back on an MD5 encryption scheme. If OpenSSL exists, but isn’t configured properly the process just fails there.
After some poking around I found that my OpenSSL installation was throwing and error regarding “/usr/syno/ssl/openssl.cnf” not exisiting. After reading this post I created this folder structure and the file and “voila” OpenSSL ran without the error and I could add my sites! The actual full path was: C:\usr\syno\ssl\openssl.cnf