Arc diff fail to upload binary file

arcanist ceb082ef6b2919d76a90d4a53ca84f5b1e0c2c06 (23 Jul 2020)
git version 2.7.4

When I issue arc diff with a commit has binary file changes, I got below error message:

Failed to upload binary “xxx.dat”.
Continue? [Y/n] Y
Uploaded binary data for “xxx.dat”.
Upload complete.

Even it shows “Upload complete”, the binary content in revision is not correct.
I issue arc patch --revision YYY, the command show merge conflict also.