Acronis plugin for cPanel/WHM produces 404 error and does not work on cPanel version 100 (with the new default Jupiter theme).
A temporary incompatibility between the filesystem path where plugins for the new Jupiter theme in cPanel need to be installed (where cPanel expects them to be placed), and where the Acronis plugin installer 1.6.5 places its files.
A temporary fix is possible, by symlinking the new location (which Jupiter-theme plugins need to use) to point to the old location where the current Acronis plugin installer puts its files:
ln -s /usr/local/cpanel/base/frontend/paper_lantern/acronisbackup /usr/local/cpanel/base/frontend/jupiter/acronisbackup
The issue has been fixed in build 388 of Acronis plugin for cPanel/WHM. Please make sure to update to this build or install from it to fix the issue.
Changelog/Release notes for all recent releases of the plugin are available at https://solutions.acronis.com/cpanel/ > Release notes.