zsync_legacy: EOF from server

[probonopd]

root@User-ghostbsd:/usr/local/ghostbsd-build/iso # /home/User/Downloads/zsync2-63-1608115-x86_64.AppImage  "https://github.com/probonop
d/ghostbsd-build/releases/download/patch-1-14.3/GhostBSD-25.02-R14.3p0-GERSHWIN.iso.zsync"
zsync2 version 2.0.0-alpha-1 (commit 1608115), build 63 built on 2023-03-04 00:30:21 UTC
Checking for changes...
Using CA bundle found on system: /etc/ssl/cert.pem
Using CA bundle found on system: /etc/ssl/cert.pem
/usr/local/ghostbsd-build/iso/GhostBSD-25.02-R14.3p0-GERSHWIN.iso found, using as seed file
Target file: /usr/local/ghostbsd-build/iso/GhostBSD-25.02-R14.3p0-GERSHWIN.iso
Reading seed file: /usr/local/ghostbsd-build/iso/GhostBSD-25.02-R14.3p0-GERSHWIN.iso
Usable data from seed files: 88.418418%
Renaming temp file
Fetching remaining blocks
Downloading from http://https/usr/local/ghostbsd-build/iso/GhostBSD-25.02-R14.3p0-GERSHWIN.iso

#################--- 88.4%zsync_legacy: EOF from server

zsync_legacy: Other error? -1
failed to retrieve from /usr/local/ghostbsd-build/iso/GhostBSD-25.02-R14.3p0-GERSHWIN.iso, status -1

What is zsync_legacy and what might be causing this error?