about the “warning! wordpress encrypts user cookies” error

Upgrading from older versions of WordPress is designed to go without hitch, and depending on the setup and the two versions involved, you may encounter some hangups along the way.   Depending on your version of WordPress, you should find something like this **#@+ * Authentication Unique Keys and Salts *. followed by set of 3, 4, or constant definitions.   WP 2.6 has three secret keys define define define.   WP 2.7 thru 2.9 have four secret keys define define define define.   It means that the number of Unique Keys and Salts may not be the same.   and you upgrade to WordPress 5.0, you will need to add the five missing constants, so that WordPress can operate and without error..   you can fix the error by simply replacing your existing secret keys with brand new set.   To do so, visit WordPress Keys & Salts Generator, copy the results, and replace your existing keys with the freshly generated code.   just make sure that your new version of WordPress has the number of secret keys defined.   Check out the previous section for list of WP versions and their number of Unique Key salts...   Read more