On Wednesday, Facebook experienced a major but partial outage that lasted most of the day. In my personal experience, I first noticed this when I tried to send a photo through Facebook Messenger and it kept failing, although I was still able to send and receive messages. Later in the day, I realized WhatsApp was also experiencing issues when I couldn't send messages. On Thursday, Facebook tweeted that the interruption of many Facebook and its family of apps and services was due to a server configuration change. Everything seemed back to normal for me later on Wednesday night. According to...
Source: https://www.gsmarena.com/wednesdays_facebookinstagramwhatapp_outage_was_due_to_a_server_configuration_change-news-36031.php