Roku Streaming Stick F21 Error Code Fix

by

What This Error Means

F21 means the device on that HDMI input failed its startup or self-check. In the real world that usually means either your Roku Streaming Stick can’t boot, or your TV is throwing its own F21 error while the Roku is plugged in.

Official Fix

Roku doesn’t publish a specific F21 code, so you follow their standard “won’t boot / weird screen” checklist.

  • 1. Kill the power properly. Unplug the Roku power cable from the wall (or TV USB) and the Roku from HDMI. Wait 60 seconds. Plug HDMI back in firmly. Then plug power back into a wall outlet, not the TV.
  • 2. Use the right power brick. Use the original Roku adapter if you have it. If not, use a known-good 5V adapter rated at least 1A. Weak power = boot failures and random codes.
  • 3. Try another HDMI port. Move the stick to a different HDMI input on the TV. Note which ports actually work; a bad HDMI port can fake a “Roku” problem.
  • 4. Try another TV or monitor. If you can, plug the Roku into a different TV. If it boots fine there, the problem isn’t the Roku; it’s the original TV or its HDMI board.
  • 5. Forced restart / factory reset. If you can at least see a Roku logo or menu:
    • Go to Settings > System > Power > System restart first.
    • If F21 or lockups keep coming back, do a full reset: Settings > System > Advanced system settings > Factory reset.
  • 6. Hard reset with the button. If the screen is stuck and menus are useless: find the tiny RESET button or pinhole on the stick.
    • Power the Roku.
    • Press and hold RESET for about 20 seconds, then release.
    • Wait a full minute to see if the Roku setup screen appears.
  • 7. If it still throws F21 or won’t boot: At that point Roku’s own guidance is: if different power, different HDMI ports, different TVs, and a factory reset don’t clear it, replace the stick.

If you unplug the Roku and the TV still shows F21 on that HDMI input or on other inputs, the error is your TV, not the Roku.

The Technician’s Trick

Here’s what techs actually do in the field with a “Roku F21” call.

  • 1. Prove who really owns F21 – Roku or the TV.
    • Unplug the Roku from HDMI completely.
    • Switch the TV to a built-in app (Netflix, YouTube) or antenna input.
    • If you still see F21 anywhere on the screen, it’s a TV fault (panel/main board), not Roku.
    • If it disappears and only shows up when the Roku is in, then the Roku or that HDMI port is the suspect.
  • 2. Hard power-cycle the TV, not just the Roku.
    • Unplug the TV from the wall for 2 full minutes.
    • While it’s unplugged, hold the TV’s power button (on the TV itself) for 15–20 seconds.
    • Plug the TV back in, turn it on, then reconnect the Roku.
    • This clears a lot of HDMI/CEC lockups that look like a Roku error.
  • 3. Get the stick away from the heat.
    • Streaming sticks cook behind the TV. Overheat = boot failures and random codes.
    • Use a short HDMI extender so the Roku hangs below or to the side of the TV with some airflow.
    • Power from a proper wall adapter, not a weak TV USB port.
  • 4. If it only fails on one specific TV.
    • Roku works fine on other TVs = your TV’s HDMI input or main board is sick.
    • If it’s an LG OLED flashing F21, check the TV’s F21–F40 table and be ready for a main-board repair or panel issue.
  • 5. If it fails on every TV, every port, every power supply.
    • That stick is done. The flash or main SoC is failing.
    • No magic remote combo fixes bad silicon. Replace the Roku.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: Stick is under ~3 years old, responds to a proper power brick + HDMI extender + factory reset, or turns out to be a simple TV/HDMI glitch.
  • ⚠️ Debatable: Out of warranty, only fails on one pricey TV, or you’re looking at a TV HDMI board repair that costs real money but the panel is otherwise perfect.
  • ❌ Replace: Roku fails on every TV and every power supply after a hard reset, or the TV itself needs a main board/panel that costs close to a new set.

Parts You Might Need

As an Amazon Associate we earn from qualifying purchases.

See also

Seeing F-codes on other gear too? These breakdowns keep the guesswork out of it: