When the OBS replay buffer won't work, the cause narrows down to fewer things than you'd think. Most of the time the buffer simply is not turned on, the save hotkey is unassigned or conflicts with another key, the save path cannot be written to, or memory capacity is insufficient. Go through them one by one in order and almost everything is resolved. This article focuses not on how to set it up but on troubleshooting by cause when it won't work despite already being set up.
First, narrow down the likely causes
Whatever the symptom, it is highly likely one of the four below. Checking in order from the top is fastest.
- Buffer off or not started: you only enabled it in settings but did not press Start Replay Buffer, or you did not restart OBS after turning it on
- Hotkey problem: the save hotkey is empty, or it conflicts with the game's or another program's key
- Save-path problem: the recording save folder does not exist, has no permission, or is a network drive so the file cannot be written
- Memory or capacity problem: the maximum replay time is set too long so RAM is insufficient, or there is no free disk space
Cause 1. The buffer is off or did not start
This is the most common cause. Under Settings then Output the Enable Replay Buffer checkbox must be on, and after turning it on you often have to fully quit OBS once and reopen it for it to apply. If you only enable it without restarting, the save item itself does not appear. After restarting, check whether the Start Replay Buffer button is visible in the control panel on the right of the OBS main screen, and whether you actually pressed that button before the game. If you do not press Start, nothing is held in memory, so there is no video to save even when you press the hotkey.
Cause 2. The hotkey is empty or conflicts
If the buffer is running but it won't save when you press the hotkey, nine times out of ten it is a hotkey problem. Go to Settings then Hotkeys and check whether a key is actually entered in the Save Replay item. In recent versions this item has been moved down to a Replay Buffer section far down the list, so it is often overlooked when it is empty. If the key is empty, nothing responds no matter how much you press.
If it won't work even though a key is assigned, suspect a conflict. If it overlaps with an in-game control key or a global hotkey from another program like the Discord or NVIDIA overlay, the signal does not even reach OBS. Try changing it to a key rarely used in games like F9, or a Ctrl or Alt combination. In particular, there are cases where the hotkey does not register when the game runs in fullscreen (exclusive fullscreen); switching to borderless window mode resolves most of them.
Cause 3. The file cannot be written to the save path
If the buffer is running and the hotkey presses but only the file won't remain, look at the save path. If the recording path under Settings then Output points to a folder that does not exist, is a location with no write permission, or is an external or network drive that loses its connection, saving fails silently. Change the path to an existing folder on a local drive and check that there is enough free disk space. The save format is also worth checking. Leaving it as mp4 can, in certain situations, corrupt the file or fail to keep it, so mkv is safer for replay and recording.
If you are unsure whether it even saved, open the recent log under the top menu Help then Log Files in OBS. The save attempt and the failure reason are recorded there, so you can pinpoint whether it is a path-permission problem or an encoder problem.
Cause 4. Memory or capacity is insufficient
The replay buffer always holds video equal to the maximum replay time in RAM. If you set this value large, like 120 or 300 seconds, or use high-quality settings like 1080p and 60fps, memory usage rises sharply, so on a PC short on RAM the buffer start itself fails or OBS becomes unstable. Try lowering the maximum time to 20 to 30 seconds and reducing the resolution and frame rate. Also, if the destination drive has no free space, the file naturally won't remain, so check disk capacity together.
An alternative with no buffer setup or hotkey: DOR automatic save
That covers the causes to check when the OBS replay buffer won't work. But if repeating this check every time is itself a hassle, an approach with no buffer or hotkey in the first place becomes the answer. DOR does not require you to enable, start, and assign a hotkey like a replay buffer does. That is because it auto-detects in-game kills and highlights and saves those moments as clips.
Leave it installed, and the moment you launch a supported game like Valorant or League of Legends it works on its own, and when you close the game the highlights are already gathered as clips. Steps like enabling the buffer, restarting, assigning a hotkey and checking for conflicts, and verifying the save path disappear entirely, so there is no cause to hunt for at all. NVENC hardware encoding is the default, so the load is light too, and it's free with no watermark.
In short, if you want to handle broadcasting and editing yourself and hand-pick which moments to save, pinpoint the cause and fix your OBS replay buffer. Conversely, if you are tired of hunting for the reason it won't save every time and your goal is to reliably keep only the good moments, DOR, which removes that process through automatic detection, takes the least effort.
