Travis failed to upload cache

Hi, my build succeeds but it fails to upload the cache. There is no message so I’m not sure what the issue is:

store build cache
changes detected, packing new archive
uploading hieu_run_test_in_docker/cache-amd64-linux-bionic-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855--compiler-gcc.tgz
failed to upload cache

Can someone help me look why it fails?