OBS "Starting the output failed": how to find the cause and fix it

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This OBS popup is a catch-all: the stream or recording could not start, and the real reason is only in the OBS log. Most often the hardware encoder (NVENC, AMF or QSV) failed to start, so updating the graphics driver or switching to the software x264 encoder usually gets you going.

Applies to:OBS StudioWindows, Linux and macOS, many versions
On this page

What it means

The message "Starting the output failed. Please check the log for details." appears in OBS Studio when you click Start Streaming or Start Recording and the output cannot begin. It does not say why. A note under it reminds NVENC and AMD encoder users to keep their video drivers up to date.

Because the popup is generic, there is no single fix. The cause is written in the OBS log, so the quickest route is to read one line there and then pick the matching fix below. If your message is about saving the file instead, see OBS "Error opening file for writing".

Symptoms and causes

You are likely dealing with this problem if:

  • The popup appears right after you press Start Streaming or Start Recording.
  • The log contains "Failed to open NVENC codec: Generic error in an external library".
  • The log says "No NVENC capable devices found".

The usual causes, most common first:

Hardware encoder fails to start
An outdated or corrupt graphics driver, a GPU that does not support the encoder, or QSV selected when Intel is not your primary graphics adapter. The OBS hardware-encoding page says to use the hardware encoder of your primary graphics adapter and to install the latest drivers.
Canvas or output resolution too large for NVENC
Forum reports say NVENC fails above roughly 4096x4096. A very wide multi-monitor canvas (5120x1440) triggered "No NVENC capable devices found". This comes from community posts only.

How to fix it

Work through these in order. They start with the quickest, safest checks and move to deeper repairs; stop as soon as the problem is gone.

1.Read the OBS log

Easy

The popup hides the real error. The first failure line after you pressed Start tells you which fix below applies.

  1. Try to start the stream or recording once so the error is written to the log.
  2. In OBS, open Help, then Log Files, then Show Log Files, and open the newest file. Alternatively choose Upload Current Log File if you need to ask for help.
  3. Find the first error after the start attempt. NVENC or encoder lines point to the fixes below.

2.Update the graphics driver

Easy

The popup itself and the OBS hardware-encoding page both point to outdated drivers for NVENC and AMD encoders.

  1. Download the latest driver from NVIDIA, AMD or Intel, depending on your graphics adapter, and install it.
  2. Restart the computer, open OBS and try again.

3.Switch to the software encoder (x264)

Easy

x264 does not depend on the GPU, so it shows whether the hardware encoder is the problem. It uses more CPU.

  1. Open File, then Settings, then Output.
  2. Set the Video Encoder to the software option (x264) under both Streaming and Recording. Label names differ between OBS versions, so pick the x264 or Software entry.
  3. Click Apply, then OK, and start again. If it works, you can keep this or continue below to restore hardware encoding.

4.Match the hardware encoder to your main GPU

Easy

OBS advises using the hardware encoder of your primary graphics adapter.

  1. In Settings, Output, choose NVENC on an NVIDIA GPU, AMF on an AMD GPU, and QSV only if the Intel graphics is your primary adapter.
  2. If your NVIDIA card is old, check that it supports NVENC. Forum replies say a GeForce 750 Ti, a 900-series or newer is needed, and that a 930MX does not support it.

5.Reduce the canvas and output resolution

Easy

A canvas beyond what NVENC accepts can give "No NVENC capable devices found".

  1. Open Settings, then Video.
  2. Set Base (Canvas) Resolution and Output (Scaled) Resolution to 1920x1080 or lower, then click Apply.

Check that it worked

  • Click Start Streaming or Start Recording: no popup appears and the button changes to Stop.
  • For a recording, stop it after a few seconds and play the saved file.

If it still fails

  • Upload the current log (Help, Log Files, Upload Current Log File) and ask on the OBS Forums with the link. The log line is what others need to help you.
  • Keep using the x264 software encoder if the hardware encoder still fails after a driver update.
  • One write-up reports that reinstalling OBS did not help, so do not count on it.

Sources

  1. Hardware Encoding (KB)Official · OBS Project
  2. Can't use NVENC encoder. Starting the output failed. · OBS Forums
  3. FIX: Starting the output failed in OBS Studio · wintips.org

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