Build uboot failed

When I compile the SDK, I get the following error: Couldn’t open blob from ‘fit/uboot.itb’: Permission denied. How should I solve it?

Installing required packages
sudo apt-get install git-core gnupg flex bison gperf build-essential zip curl
zlib1g-dev gcc-multilib g+±multilib libc6-dev-i386 lib32ncurses5-dev x11protocore-dev libx11-dev lib32z-dev ccache libgl1-mesa-dev libxml2-utils xsltproc unzip python-pyelftools python3-pyelftools device-tree-compiler libfdt-dev libfdt1 libssl-dev liblz4-tool python-dev