Error after logging in to the Magento Admin

Details

The requested URL /magento2index.php/admin/admin/dashboard/index/key/0c81957145a968b697c32a846598dc2e/ was not found on this server.

Note the lack of a slash character between magento2 and index.php in the URL.

Solution

The base URL is not correct. The base URL must start with http:// or https:// and it must end with a slash (/). Run the installation again with a valid value.