Samsung's own PC software installs a USB driver as part of its setup, and that driver doesn't always play well alongside the plain Samsung USB Driver package or the Google USB Driver used for ADB. The result is a phone that connects fine for file transfer through Smart Switch, but shows as unauthorized, invisible, or "unknown device" the moment you try adb devices or open Odin for a firmware flash.
Smart Switch (and Kies before it) bundles a driver tuned for its own proprietary sync protocol rather than the plain ADB interface most third-party tools expect. When both Smart Switch's driver and a separately installed Samsung USB Driver or Google USB Driver are present, Windows sometimes binds the phone's USB interface to whichever driver was installed most recently or has higher priority in its internal driver ranking, regardless of which one you actually need active for a given task. Background services that Smart Switch installs can also hold onto the COM port or USB interface the phone uses, blocking Odin or adb from claiming it even if the driver itself is technically correct.
Open Device Manager while the phone is connected. If the phone shows up without a warning icon but adb still reports no devices, or Odin's log shows "Added" then immediately "Removed," that's a strong sign a background Smart Switch process is grabbing the interface rather than a missing driver.
Check Task Manager for background processes named similarly to SmartSwitch, SsAgent, or Samsung Kies (on older systems that still have Kies installed) running even when the main application window is closed — these background agents are the usual culprit.
adb devices or reopen Odin.If closing the background process alone doesn't fix it, the driver binding itself may need to be reset:
This gives Windows a clean slate with only the driver you actually need bound to the device, rather than two competing driver packages both claiming the same interface.
Odin needs the phone in Download Mode, which presents a different USB interface than normal ADB mode. A Smart Switch background service holding the normal ADB-mode interface generally won't interfere once the phone is actually in Download Mode, but it's still worth fully closing Smart Switch before opening Odin, since some versions of the background agent poll for connected Samsung devices continuously and can momentarily grab the COM port Odin is trying to use, showing up as a red "Fail" or the ID:COM box staying empty even though the phone shows the Download Mode screen. See our Odin USB driver and Download Mode guide for the full Download Mode entry sequence.
If you need both Smart Switch for backups and adb for development work on the same machine, the more durable fix is disabling Smart Switch's auto-start background agent (in its own settings menu, look for an option like "run in background" or "auto run") rather than uninstalling it outright. This keeps the software available when you launch it manually while preventing its background process from competing for the USB interface the rest of the time.