Agentstrap isn't working
Nothing happens, launches fail, or features do nothing. Work through these in order.
These are the failures people report most often, ordered by how often they turn out to be the cause.
1. Nothing happens when you click Launch
| Check | How |
|---|---|
| Is Windows asking for administrator rights and failing? | Accept the UAC prompt. If it can't be shown, Agentstrap can't install Roblox. |
| Is the Media Feature Pack installed? |
Roblox needs mfplat.dll. Without it the launch fails with
"Launch failed — Windows Media Feature Pack (mfplat.dll) is missing." Install
Media Feature Pack for Windows from Windows Optional Features.
|
| Is the protocol handler registered? |
Command Center → Repair Roblox links. This re-registers roblox:// and
roblox-player:// without needing administrator rights.
|
| Is Roblox actually installed? | The Command Center's Roblox Player card says Installed or Not detected. If it isn't installed, the next launch installs it — which needs internet access. |
2. The launcher opens but Roblox never appears
- Wait for the download. Roblox can be a large download on a slow connection.
- Check the Command Center's Last launch card. It distinguishes Launch cancelled, Launch failed and Launch did not complete.
- Check the Roblox install folder for
RobloxPlayerBeta.exe. If it's missing, see Repairing a broken Roblox install. - If antivirus or a corporate policy is blocking the launch, Agentstrap's log will record it.
3. A feature does nothing
| Symptom | Likely cause |
|---|---|
| Server location, overlay, game history or Discord presence all dead | Activity tracking is off. It's the master switch for all of them. |
| Features work, then stop after you toggle activity tracking | Turning activity tracking off switches the dependent features off. Turning it back on does not turn them back on — re-enable each one. |
| Fast Flags have no effect | The client was already running. Flags are applied at launch, so restart Roblox. Also check that Allow Agentstrap to manage Fast Flags is on. |
| Fast Flags have no effect at all, in any version | Roblox's September 2025 allowlist. Most custom flags are simply ignored by the player now. See Engine settings. |
| Mods disappeared | The Modifications folder was cleared, or Roblox was reinstalled in a way that bypassed the copy step. See Modding. |
| The overlay never appears | Activity tracking off, or the game is in exclusive fullscreen, or Roblox's logging changed. See Server connection overlay. |
| Matchmaker does nothing | The matchmaker is off, or no place ID is set, or no public server met your minimum free slots. See Matchmaker. |
4. Settings won't save
- You have to press Save in the bottom-right of the settings window. Nothing is written to disk until you do.
- If the window is closing without a prompt, the save already succeeded.
- If
Settings.jsonis corrupt, Agentstrap falls back to defaults and says so. The Diagnostics page flags this.
5. The interface looks broken
- Try the plain theme. A custom theme file that no longer exists is a known issue — Diagnostics reports it as an invalid setting. Remove the custom theme, or use Settings → Appearance → Delete.
- Reset to defaults. The Advanced page has a reset for NEXUS, but for a full reset, delete
Settings.jsonfrom the install folder and restart Agentstrap. You will lose your preferences. - Try English. Several newly added pages still use hardcoded English. If the interface looks half-translated, that's why.
6. Collecting more information
Agentstrap writes a log for every session. The Advanced page has Open logs and Clear logs — clearing them first gives you a clean log with only the failing session in it.
One request before you post.
Copy the diagnostics report and check it yourself first. Nine times out of ten it names the exact check that failed.