Troubleshooting

Work from the host outward: first the host, then the network, then the device. Do not wipe data or change the show project until you know which part fails.

Prest Server does not start

REAPER

REAPER shows a message box titled Prest when Prest Server needs your attention, and writes every message to prest.log, in the UserPlugins folder of REAPER’s standard resource folder (see the REAPER guide).

Message	What to do
Prest could not start: … could not bind to 0.0.0.0:80: address in use; backup ports 8418, 8419, 8420, 8421, 8422 were also unavailable	Another program holds the ports: another REAPER with the plugin, Live with the Control Surface, Prest, or a web server. Close it, or set another Server Port.
Prest could not start: Invalid Prest server port …	PREST_PORT is not a port number.
Prest could not start: Invalid Prest bind address …	PREST_BIND_ADDR is not an IP address.
… so Prest is serving on port 8418 instead. Open http://prest.local:8418/ — addresses without the port will not reach it.	Port 80 was taken, or, on Linux, not allowed. Prest Server is running: open the address it names, or see Ports.

No message, and no page? Check that the plugin file is in the UserPlugins folder REAPER uses (Options, Show REAPER resource path in explorer/finder), that only one Prest Server plugin file is there, and read prest.log.

Releases after 0.1.1 say Prest Server could not start and title the box Prest Server.

Ableton Live

Live shows Prest Server’s messages in its status bar, starting with Prest: (Prest Server: in releases after 0.1.1), and writes them to its Log.txt.

What you see	What to do
Prest is missing from the Control Surface list	The Prest folder is not in the Remote Scripts folder of Live’s User Library, or Live was open while you installed. Check the folder and restart Live.
Prest: prest-ableton not found (prest-ableton.exe on Windows)	The bridge is missing from the Prest folder. Install again.
Prest: prest-ableton not executable	The bridge file lost its permission to run. Install again with the install command.
Prest: failed to launch bridge: …	The bridge could not start; the reason follows. On macOS, a copy downloaded with a browser can be blocked: clear the download flag as the install steps show.
Prest: … could not bind to 0.0.0.0:80: address in use; backup ports … were also unavailable	Another program holds the ports, as for REAPER above.
Prest: bridge exited unexpectedly with status …	The bridge stopped. Live starts it again every 3 seconds. In 0.1.1 this message can hide the reason: look for lines starting Prest[bridge]: in Log.txt.
Prest: arrangement refresh failed	Live’s arrangement could not be read; Log.txt says why, for example Locator … has a negative position.

When Prest Server falls back to a backup port, Live shows Prest: … so Prest is serving on port 8418 instead in the status bar. In 0.1.1 Live’s start-up can hide it; Log.txt keeps it. In the next release it stays in the status bar until the first play.

Log.txt records Prest: bridge ready on port 80 (or the port it uses) when the bridge is running.

Prest

Prest Server is built in. If it cannot start, or stops, Prest shows a notice starting with Prest Server stopped: and the reason. See Stage screens.

Cannot connect

1. Check that the host shows no Prest Server message.
2. Check that the device and the host computer are on the same band-owned network.
3. Open http://prest.local/, with the port if the host uses one (http://prest.local:8418/).
4. If the name does not open, use the host computer’s IP address.
5. Check the router’s client isolation and guest settings, and the host computer’s firewall.
6. On macOS 15 and later, check that REAPER, Live, or Prest has local network access.
7. Avoid public, venue, and guest Wi-Fi: Prest Server has no login, so anyone on the network could control the show.

See Network and security for discovery, ports, and firewalls.

The page says Waiting, Offline, or Standby

• Waiting: the page reaches Prest Server, but the host has not answered for about 3 seconds. Look at the host computer: a dialog open in REAPER or Live, for example a save prompt or a missing-files prompt, holds it up. Close the dialog.
• Offline: the page cannot reach Prest Server. It reconnects by itself when it can; see Cannot connect.
• Standby: this host is following another Prest Server on the network. If you did not set up a backup computer, set a Rig Pairing Key, or turn off Announce on the Network (mDNS), and restart the host. See Other Prest Servers on the network.

Show library problems

• The badge reads Invalid. The folder does not exist on the host computer, is not a folder, or cannot be read. The path is on the host computer, not on the device. The first-run guide shows the reason: Path does not exist or is not a directory, Directory is not readable, or Folder path cannot be empty.
• The badge reads Pending. The path has not been checked yet: click or tap outside the field.
• Project root folder is not set. Please configure it in Prest settings. No show library folder is set. Set it in Setup. In Prest and the next release, Editor and Performance say No show library folder is set, so songs cannot load.
• Project file does not exist: … The song’s project was moved or renamed in the show library. Edit the song and pick its project again, or delete the song and add the project again.
• No + Add All Projects button. Every project is already in the catalog, or the folder holds no projects of this host’s kind: REAPER lists .rpp files, Live .als files, Prest .prest files.

Adding projects stalls or skips projects

• REAPER, 0.1.1, the run stops. A project uses media files that are missing, and REAPER is waiting on its dialog asking for them. Answer it in REAPER. In the next release such a project is skipped instead: Project «…» has missing media files — skipped: and the files.
• Live, many projects reported “Could not open project «…» — skipped”. Live was still busy opening a Set, or a dialog is open in Live. Finish what Live shows, wait until the Set is open, and choose + Add All Projects again: it adds only what is missing. Live’s own reasons are Another Live Set is already being opened. and Timed out waiting for Ableton Live to open the Set. Check Live for an open dialog and finish the switch there.
• Live, 0.1.1, backup copies listed. See Prepare the show library.

Wrong or missing songs

1. Check the song markers or locators: S\Name starts a song; plain names are ignored. See Songs.
2. Read the Import Issues box after adding projects; see Editor.
3. If you added markers after adding the project, delete its song and add the project again.
4. On the Performance page, a song that is in no setlist is listed only in All Songs, which Setup can hide on a device.

Lyrics or chords are missing

1. Check that the song’s project is the one open in the host.
2. Check the track names: Lyrics and Chordtrack, in any case.
3. REAPER: lyrics are MIDI lyric events on the Lyrics track, and chords are the notes of items on the Chordtrack track. Live: they are the names of arrangement clips on those tracks, not Session clips.
4. Check that the lyrics and chords lie between the song’s start and end markers.
5. Read the message in place of the lyrics; see Lyrics and chords.

The transport does not do what you expect

• Play plays another song. In 0.1.1, Play plays whatever the host has open. Choose the song in the song picker first. In Prest and the next release, Play loads the song shown when it is not loaded.
• Prev and Next stop the music. They open the previous or next song, stopped. While the host plays, choose a song in the song picker to queue it, then use Play Next.
• Playback stops at the end of a song. In a project with several songs, the host stops at the next song marker.
• The host does something by itself. Another device, or another Prest Server on the network, is controlling it. See Network and security.

To report a problem, stop the show safely, reload the page, and note the host’s state, the page’s state, the selected song, and the action that went wrong.

Backup import fails

• Select a Prest backup file (.rpbak).: the file does not end in .rpbak.
• Backup file is not a valid Prest backup.: the file is damaged or is not a Prest Server backup.
• Failed to read backup file.: the browser could not read the file. Copy it to the device again.

Keep the original file unchanged, and do not wipe the catalog while an import fails.

The page looks stale

Reload the page first. Clearing the browser’s data for the site resets that device’s settings and first-run guide; songs and setlists stay on the host.

What to send with a report

The Prest Server version from the releases page (or the Prest version), the operating system, the host and its version, the browser and its version, the address you opened, the connection state, what you did, and the relevant lines of prest.log or Live’s Log.txt. Use the feedback form.