OBS "An Error Occurred While Starting the Output" - Fix

OBS "An Error Occurred While Starting the Output": Fix

You press Start Recording and OBS returns An error occurred while starting the output, sometimes followed by a reference to the log file. The recording never begins, and no file appears.

There is a widespread assumption that this is the same problem as the encoder failure people hit when they press Start Streaming. Often it is not. When the output being started is a recording, OBS has to do something it never does when streaming: create a file, in a specific folder, in a specific container format, holding a specific number of audio tracks. Any one of those four can fail on its own, with the encoder working perfectly.

So this guide works the recording-specific causes first, in the order they actually occur, and only sends you to the encoder if those come up clean.

Was it the streaming button? If the dialog said Starting the output failed. Please check the log for details and appeared on Start Streaming, that is the encoder initialisation path. OBS "Starting the Output Failed": Fix works that one.

Step 1: Verify the Recording Path Exists and Is Writable

This is the cause in the clear majority of cases, and it takes thirty seconds to rule out.

OBS stores the recording folder as an absolute path. It does not re-check that the path is valid until you press record. So the error appears the first time you record after any of the following:

• The external drive or SD card you were recording to is not plugged in.
• A network or NAS path is not mounted, or the machine is off the VPN that reaches it.
• The folder was renamed, moved, or deleted since you set it.
• The drive letter changed, which Windows does routinely when USB devices are connected in a different order.
• You are recording into a folder inside Program Files, Windows, or the root of C:\, where standard user accounts cannot write.

To check and reset it:

1. Open Settings > Output.
2. If Output Mode is Simple, look at Recording Path. If it is Advanced, open the Recording tab and look at Recording Path there.
3. Copy that path into File Explorer or Finder and confirm it opens.
4. Click Browse, choose a folder inside your user directory — C:\\Users\\<you>\\Videos on Windows, ~/Movies on Mac — and click Apply.

Test with a plain local folder even if you intend to record elsewhere. If it records into Videos and fails on your intended destination, the destination is the problem and you have your answer.

A note on cloud-synced folders. Recording directly into OneDrive, Dropbox, iCloud Drive or Google Drive folders causes this error intermittently rather than consistently, because the sync client locks files while uploading them. It is genuinely hard to diagnose because it works most of the time. Record locally and move the finished file afterwards.

Step 2: Check the Filename Formatting String

OBS builds each filename from a formatting template, and a template containing a character the file system forbids produces a file creation failure and this exact error.

1. Open Settings > Advanced.
2. Find Filename Formatting under the Recording section.
3. The default is %CCYY-%MM-%DD %hh-%mm-%ss.

If you have customised it, remove any of these characters: \\ / : * ? " < > |. The colon is the one that catches people, because writing a template like Demo %hh:%mm looks entirely reasonable and produces an invalid Windows filename. Reset it to the default to test.

While you are in this section, if Automatically remux to mp4 is ticked and you are troubleshooting, untick it temporarily so it is not a variable.

Step 3: Resolve Container and Audio Track Conflicts

This is the cause most likely to be missed, because everything in Settings looks correct.

MP4 and multiple audio tracks. In Simple output mode, MP4 holds one audio track. If you have enabled additional tracks — a separate mic track, a separate desktop track, a track for a game — and the recording format is MP4, the output cannot be created.

• Advanced mode: open Settings > Output > Recording and look at the Audio Track checkboxes. Either tick only track 1, or change Recording Format to MKV, which holds as many tracks as you give it.
• Simple mode: set Recording Quality to something other than Same as stream, and set Recording Format to MKV.

Encoder and container mismatch. Not every encoder can be written into every container. HEVC and AV1 output into MP4 fails on some builds and driver combinations; the same encoder into MKV succeeds. If your Video Encoder is an HEVC or AV1 variant, switch it to the H.264 equivalent, or switch the container to MKV.

MKV is the right default for recording anyway. It survives a crash or power loss, where an MP4 that was still being written is unrecoverable. Remux to MP4 afterwards with File > Remux Recordings, which is a container rewrite rather than a re-encode, so it is fast and lossless. OBS MKV vs MP4: Which Should You Use? covers the trade in full, and How to Convert OBS MKV to MP4 covers the conversion.

Custom Output (FFmpeg). If Type is set to Custom Output (FFmpeg), the container, video encoder and audio encoder are all set by hand and any invalid combination fails here. Unless you specifically need it, set Type back to Standard.

Step 4: Rule Out the Replay Buffer and File Splitting

Two optional features start their own outputs, and either can be what actually failed.

Replay buffer. If it is enabled, OBS reserves memory for it before recording starts, and an unreachable reservation fails the output. Open Settings > Output > Replay Buffer and untick Enable Replay Buffer, then test. If recording now works, re-enable it with a shorter Maximum Replay Time and a lower Maximum Memory value.

Automatic file splitting. Under Settings > Output > Recording, if Automatic File Splitting is on, confirm the split time or size is a sane value. A misconfigured split — a size limit of zero, for instance — fails immediately.

Step 5: Only Now, Test the Encoder

If the path is valid, the filename template is clean, the container matches the tracks, and the optional outputs are off, the encoder is the remaining candidate.

1. Open Settings > Output, set Output Mode to Advanced, and open the Recording tab.
2. If Video Encoder is set to (Use stream encoder), change it to an explicit encoder. That setting inherits a broken streaming configuration into your recording, which is a confusing way to fail.
3. Set it to Software (x264) and test.

If x264 records and your hardware encoder does not, you have an encoder initialisation problem rather than an output problem, and OBS "Starting the Output Failed": Fix covers it from there. If the encoder is NVIDIA's, go straight to OBS NVENC Error: How to Fix NVIDIA Encoding Issues.

Symptom Router

Why This Class of Error Keeps Coming Back

None of the causes above is a bug. Each is a legitimate configuration OBS allows because someone needs it: separate audio tracks for post-production, custom FFmpeg output for an unusual delivery format, a network path for a shared editing volume. OBS gives you the whole surface and trusts you to keep the pieces compatible.

The cost is that the pieces drift. A drive letter changes, a sync client is installed, a second audio track is added for one project and left on, and three weeks later a recording will not start for reasons that have nothing to do with what you changed.

If your recordings are software tutorials and product walkthroughs rather than multi-track production, that surface is not buying you anything. Cubix Capture has no container to match, no track configuration to keep compatible, and no output path to go stale, on Windows and Mac. Zoom and cursor smoothing are applied while you record, so the file is publishable when you stop. The free Starter plan needs no account, which is enough to compare against your current workflow.

Keep Reading

• OBS "Starting the Output Failed": Fix for the encoder initialisation path.
• OBS Can't Find Recording: Where Are OBS Files Saved? if recording starts but you cannot locate the file.
• OBS MKV vs MP4: Which Should You Use? on picking the container that will not fail you.
• OBS "No Space Left on Device" Error: Fix if recording starts and then stops on its own.