Error: Incomplete vagrant binary after failed upgrade

Problem

When a Vagrant upgrade (via vagrant update or vagrant plugin update) is interrupted—by network failure, permission issues, or other errors—the new binary is left incomplete in the cache directory while the currently installed executable remains unchanged. Subsequent invocations can then misbehave because the cache contains partially downloaded files, yet there is no documented automatic rollback to the previous binary. This leaves users with a fragile state that must be remedied manually.

Goal

Determine a reliable path to recover from such a failed upgrade without manually reinstalling the original package.

Unresolved Questions

• Can Vagrant automatically revert to the last stable binary if an upgrade fails?
• Does the cache retain a copy of the previous executable that could be restored programmatically?
• Would a transactional upgrade model be implementable in future Vagrant releases to guarantee atomicity?