The launcher's own messages, what causes each, and what to do about it. Quoted text is what the launcher shows, except the one line that says Windows shows it. The launcher describes how each part works, and its closing section says what to attach when a problem is not on this page.

Starting the launcher

• "Phaethon is already running", then "Switching to the existing window..." A launcher is already open, and a second start brings it forward instead of opening another. Because an update can start the new launcher while the old one is still closing, a second start waits up to five seconds before it does this.
• The first-run setup opens on every start. It does so until it is finished or skipped; see The launcher. Reset App in Settings brings it back on purpose.
• A crash dialog saying that copying the launcher's data from %AppData%\JakLauncher to %AppData%\PhaethonLauncher failed. The first start of a launcher with the Phaethon name copies the older launcher's folder, and a file could not be read or written. Your settings were not changed, and the next start tries again.
• Your settings are back to their defaults. At start, a settings.json that does not parse is moved aside as settings.json.corrupt-<date>-<time> in %AppData%\PhaethonLauncher, and the launcher starts from defaults; your old values are still in that file. A settings.json that cannot be read at all is left where it is, and the launcher runs on defaults without saving over it. Either case adds a line to settings-recovery.log in the same folder.
• "Settings could not be read" with "Nothing was saved." While the launcher was running, settings.json could not be read when a change was saved, so the change did not stick and the file was left as it was. The launcher already retries a read three times when another program holds the file, so the file stayed locked, could not be accessed, or no longer parses.
• "Running as administrator". The launcher usually does not need to run elevated, and dragging mods in from Explorer may fail while it is.

Installing and updating the runtime

• A message about the install folder. The setup checks the folder as you type it; the Install Runtime dialog and Move Install check it when you confirm, with a "Can't use this location" or "Heads up" toast. An error blocks the folder: the path is empty or invalid, "No part of this path exists. Check the drive letter.", or "Can't write to this location." A warning lets you go on: the path is long enough that files nested under it may pass Windows' 260 character limit, the drive is removable, a network drive or read-only, the folder needs administrator rights to write, or it is inside OneDrive, Dropbox or iCloud Drive, whose syncing can lock the game's large files. "Windows gave this account no profile folder, so there is no default install folder. Choose one with Browse." means the setup has no folder to offer your account, and Next waits until you type or browse to one.
• "Not a valid install". Find Existing Runtime was pointed at a folder with no gk.exe in it.
• "Offline", with "Could not reach the update server. You can still play." The store did not answer the check at start. An installed runtime still plays, and the bar reads "Ready to play" with "Update server unreachable"; without a runtime it reads "Not installed. Update server unavailable." The Retry beside that line checks again.
• "Could not check for updates", with "Playing with current version". With Check for Updates on Launch off, Play checks the store itself, and the store did not answer; the game starts on the runtime you have.
• "Download failed", and the bar's button reads RETRY. A runtime file could not be downloaded. A store that answers busy is already asked again up to six times before this, and the message says what failed, such as "Connection timed out. Check your internet." or "Server error. Try again later." RETRY checks the store again, and a download started again skips the files it already completed, as long as the store still publishes them unchanged.
• A file "does not match the v... manifest after the download". The final check hashed a downloaded file and it did not match. The download stops, naming the file, and the next attempt downloads that file again.
• "The store published v... while ... was downloading", with "Starting over". A new runtime version appeared on the store during your download. The download starts over on the new version, keeping every file already on disk that matches it.
• "Quick mode auto-promoted". Quick update checks is on, but the store's manifest marks no file as required, so that check ran in full. Nothing needs doing.
• "Repair failed", with "Could not fetch manifest". Repair Files could not reach the store. Try again once the connection is back.
• "The game is running", with "Close the game before ...". Repairing, moving or uninstalling the runtime, and clearing the decompiler output, are refused while the game runs; close it and try again.

Launcher updates

• "Launcher updates are off". This copy was not installed by Setup, for example one run straight from a build folder, so it cannot update itself; install it with the install wizard.
• "Launcher update refused". The store's update feed broke one of the launcher's rules, and the message names the rule. The problem is on the store's side, and the launcher downloads nothing from such a feed.
• "Launcher update check failed", with "Could not reach the update server." The store did not answer; the next start checks again.
• "Launcher update blocked". A runtime download is in progress, and updating the launcher would close it mid-file. Let the download finish or cancel it, then choose Update Now again.
• Windows SmartScreen shows "Windows protected your PC" before the installer runs. That release was published unsigned, or is signed but new enough that SmartScreen does not know it yet. Choose Run anyway to start it.

Importing a disc

The Import button explains itself when it is disabled: hover over it.

Why Import is disabled	What to do
"Choose the disc image first."	Set the disc image path on the Disc tab, or use Browse.
"No extractor.exe next to the runtime. Install or build the tools first."	Install the runtime from the Home page, or, with a local build, build the tools into that folder.
"An import is running." or "A rebuild is running."	Only one import or rebuild runs at a time, for any game.
The game's name, then "is running."	Close the game first.

Before it spends minutes on the extractor, the launcher reads the disc image's PlayStation 2 system file, and any of these stops the import with "Import not started":

Message	Cause
"This file is not a disc image: there is no ISO 9660 volume descriptor where one belongs."	The file is not an ISO image.
"The disc image is shorter than its own volume descriptor says; the dump is incomplete."	The dump was cut short; make it again.
"The disc has no SYSTEM.CNF at its root, so it is not a PlayStation 2 disc."	The image is some other kind of disc.
"This disc is Jak II (serial SCUS-97265), not Jak 3."	The disc is for another game's card; import it from that game's page.

A serial the launcher does not list is not refused here; the runtime's extractor decides. The serials the launcher knows are on Getting started.

When a stage of the import fails, the toast names the game and the stage ("import failed at extract", "at decompile" or "at compile") and gives one of these:

Message	What it means
"The disc image or folder does not exist any more."	The image moved or was deleted since you chose it.
"The disc image path could not be opened."	The file is there but could not be read.
"The disc image is not the size of a PlayStation 2 disc; it may be truncated or not an ISO."	Make the dump again.
"No game executable was found on this disc. Is it a PlayStation 2 game image?"	The image holds no game.
"This disc is not one the runtime's database knows; the retail discs it knows are listed in its extractor."	The runtime's extractor does not know this disc's serial.
"The game executable on this disc does not match any known ... release."	The disc names the right game but not a release the extractor knows.
"The disc's contents do not match what the fork expects for this release; the image may be modified or damaged."	The image differs from the retail disc.
"The disc extracted to a different number of files than this release has; the image may be incomplete."	Make the dump again.
"The extracted files do not hash to the known release; the image may be modified or damaged."	Make the dump again.
"The extraction itself failed part way. Check free space on the drive and try again."	Usually a full drive.
"This folder was not imported for ... by the launcher, so the ... stage cannot use it. Import the disc again."	The extracted disc in the install folder came from somewhere else.
"Decompilation failed."	The decompiler stopped; its last lines are in the launcher log.
The game's name, then "build failed in the ... stage."	The compiler stopped; its last lines are in the launcher log.
"This runtime's extractor does not know ...: it was built without ..."	The installed runtime was built without that game.
"The extractor rejected its arguments. This is a launcher defect; the log tail has the line it printed."	Report it through the issue forms with the launcher log.

The launcher log holds every line the extractor printed; it needs debug tooling, as The launcher describes under Logs. Canceling an import keeps whatever was extracted so far for the next attempt. Canceling a rebuild leaves the build part old and part new until the next rebuild runs.

• A warning that the game's build record was not written. The import or rebuild finished, but the launcher could not save the record of which runtime built the game, so it will ask for a rebuild that may not be needed.

Playing

• The Display, Audio, Controls and Game tabs are covered. "Import the disc first" means the game has no data yet. "Play" and the game's name, then "once to unlock", means the game has not written its settings file yet, which it does the first time it runs. "Play" and the game's name, then "remastered once to unlock", means the same for the remastered preset's file, which the tabs edit while Remastered is checked and the game writes the first time it runs with Remastered on. "Locked while" and the game's name, then "runs", means the game is running and would write its settings back over your change when it exits; close it first.
• "Settings file unreadable". The game's settings file under %AppData%\Phaethon\<game>\settings did not parse, so the tabs do not offer its fields, and the launcher leaves the file for the game to rewrite.
• Debug mode or the Debug Bar tab is missing from the Game page. Both appear only while Settings, Launcher, Enable debug tooling is on and saved.
• "Update Available" when you press PLAY. Check for Updates on Launch is off, so Play checked instead and found runtime files to update. Update installs them first; Play Anyway starts the game on the runtime you have.

Signing in

These show in the sign-in window. Its details go to the launcher log under Sign-in.

Message	What to do
"Phaethon's sign-in could not be reached. Check your connection, then start over."	Check the connection, then Start over.
"Phaethon refused the sign-in. Start over to try again."	Start over for a new code.
"Phaethon's sign-in answered something the launcher cannot use."	Try again later; if it repeats, report it with the launcher log.
"The code expired before the sign-in finished. Start over for a new code."	Start over, and confirm the new code sooner.
"The sign-in was declined on the page, so the launcher stopped. You are not signed in."	The page's decline was chosen; start again when you mean to sign in.
"You signed in, but Windows Credential Manager would not keep the sign-in. Start over to try again."	Windows refused to store the sign-in token; Start over to try again.

• "No browser opened". Windows would not open a browser; open the page the sign-in window shows yourself and enter the code there.
• "Could not copy the code". Another program is holding the clipboard; type the code on the page instead.
• The profile page says "The account service could not be reached." The launcher could not reach api.playphaethon.com. Your play time shows as this PC's, marked On this PC, until it can.
• The profile page says "The account service did not accept your sign-in. Sign in again." The service refused the sign-in even after the launcher refreshed it; sign in again.
• "The saved sign-in was not removed", with "Windows Credential Manager refused. Sign out to remove it." Turning Auto Login off could not delete the stored token; Sign out removes it.
• Signed out after updating from an early launcher. Phaethon's sign-in moved to auth.playphaethon.com, and a sign-in saved at its old address cannot be used there, so the launcher deleted it without sending it. Sign in again; the launcher log records this under Sign-in.

Phaethon is a hard fork of OpenGOAL's jak-project. Naughty Dog made the games; you need your own copy of each. built from the wiki · 28 Sep 2026