After all of my websites were down, I contacted DigitalOcean’s support and they suggested me to consider resizing to a larger Droplet size because my sites were using up the memory.
Then I logged into the Control Panel, navigated to Resize and chose a new plan. I moved from the $20 plan with 2GB of Memory, 2 Core Processor and 40GB of SSD Disk to the $40 plan with 4GB of Memory, 2 Core Processor and 60GB of SSD. After pressing the Resize button, the loading ring took forever to complete and I knew there was something wrong here.
A DigitalOcean representative said my Droplet had to be copied to a physical host system with spare capacity to handle the increased resources allocated to it, which explains why this took longer than usual to perform. However, waiting for over 30 minutes is unusual. I checked the history and it seems like the process was completed a long time ago. It actually took just more than 5 minutes to resize the Droplet.
Therefore, make sure to check the Droplet’s History if the process takes too long to finish.