Install libmtp9 by entering the following commands in the terminal:
sudo apt update sudo apt install libmtp9
Media Transfer Protocol (MTP) library
libmtp is a library for communicating with MTP aware devices in POSIX compliant operating systems. It implements MTP Basic, the subset proposed for standardization. . The Media Transfer Protocol (commonly referred to as MTP) is a devised set of custom extensions to support the transfer of music files on USB digital audio players and movie files on USB portable media players.