Error updating Amazon AMI with yum
Solution 1:
You have somehow managed to install nginx and the yum repository (provided by nginx.org) you have installed along with it is not compatible with Amazon Linux. It is intended for RHEL 7 or CentOS 7. Amazon Linux is not compatible with RHEL/CentOS, and packages for these often do not work on Amazon Linux.
To resolve the problem, launch a new instance with a supported operating system distribution such as RHEL 7 or CentOS 7, and install nginx on that instance.