apr not found

The error message "apr not found" usually indicates that a required library called APR (Apache Portable Runtime) is missing on your system. APR is a library that provides a platform-independent interface for various operating system APIs, such as threading, file I/O, and network sockets.

To resolve this error, you need to install APR on your system. The specific steps to do this depend on your operating system and package manager. For example, on Ubuntu or Debian Linux, you can install APR by running the following command:

sudo apt-get install libapr1-dev

On CentOS or Fedora Linux, you can use the following command:

sudo yum install apr-devel

Once APR is installed, the error message should go away and your application should be able to find the required library.