Paradox Launcher failures have several different causes, so the correct fix depends on what you see. A blocked or quarantined bootstrapper needs an antivirus exception; a broken installation needs a clean reinstall; missing mods and playsets need their own database reset; and a JavaScript error can require the current Microsoft Visual C++ runtime. If the launcher opens normally but the game does not, troubleshoot the game or Windows separately rather than repeatedly reinstalling the launcher.
Work through the branches below in order. Start with security software because it can silently quarantine files or prevent the launcher from writing its databases.
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Identify the failure before changing files
Match your symptom to the branch that addresses it. Deleting every Paradox folder at once can remove useful data and make diagnosis harder.
| What you see | Most likely branch | First action |
|---|---|---|
| Nothing opens, or Steam reports a bootstrapper error | Antivirus quarantine, ransomware protection, or damaged launcher files | Inspect quarantine and create executable exceptions |
| A launcher JavaScript error appears | Incomplete launcher installation or missing Microsoft runtime components | Reinstall the launcher, then install the current supported Visual C++ runtime if needed |
| Launcher opens but mods or playsets are empty | Blocked writes or corrupted mod and launcher databases | Allow the executables, then reset the mod registry and launcher database |
| Launcher opens, but clicking Play does nothing or the game closes | Game files, Windows configuration, or a game-specific issue | Run the game executable directly and troubleshoot outside the launcher |
Check antivirus and ransomware protection first
Paradox Helpdesk says antivirus software commonly causes launcher startup and mod problems. A security product may quarantine a legitimate bootstrapper or block the launcher from creating files without displaying a clear error.
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Inspect quarantine before deleting anything
- Open your antivirus or endpoint-security application and view its quarantine or detected-threat history.
- Look for
bootstrapper.exeorbootstrapper-v2.exe,paradoxlauncher.exe, Steam, or the affected game’s executable. - If one of those files was flagged and you obtained the game through Steam, restore it only when you are confident the detection is a false positive. Do not permanently delete it and then continue troubleshooting a missing file.
- After restoring, run the security product’s update check and create an exception for the restored file or its installation folder.
Add the complete executable set to allowlists
Create exceptions for Steam, the game executable, bootstrapper.exe, bootstrapper-v2.exe, and paradoxlauncher.exe. If your security product distinguishes between a file and a folder rule, use the exact executable paths shown in its alert and in Steam’s local-files folder.
Check Windows ransomware protection
Windows Security’s ransomware controls, including Controlled folder access, can block legitimate write operations. Open Windows Security, review the ransomware-protection history, and allow the launcher and game executables when they were blocked. Keep protection enabled for other applications; the goal is to permit only the files you have verified.
Try the low-risk launch checks
These checks do not remove launcher data and should be completed before a reinstall.
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- Start Steam again with administrative rights. Right-click the Steam shortcut, choose Run as administrator, and approve the User Account Control prompt.
- Launch the affected game once from Steam. Starting it through Steam lets Steam rebuild or repair the launcher hand-off.
- If the launcher still fails, open the game’s Steam page, choose Manage > Browse local files, and double-click the game’s executable. This direct test separates a launcher problem from a game or Windows problem.
- Where a title or installation guide requires it, make sure Steam and the game are installed on the same Windows partition. A split installation can prevent the bootstrapper from finding expected paths on some systems.
Perform a clean Paradox Launcher v2 reinstall on Windows
A clean reinstall removes the launcher program and its residual folders. It does not replace the game’s own files, saves, or Steam installation.
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- Discover a sprawling simulated world teeming with peasants and knights, courtiers, spies, knaves and jesters, and secret love affairs.
- Explore a vast medieval map stretching from the snowswept Nordic lands to the Horn of Africa, and the British Isles in the west to the exotic riches of Burma in the east.
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- Groom your heir with the appropriate guardians or educate them yourself. If found wanting, marry them off or despatch them through other means.
- Open Settings > Apps > Installed apps (or Apps and Features on older Windows versions).
- Find Paradox Launcher v2, choose Uninstall, and finish the wizard.
- After the uninstall completes, open File Explorer and enable View > Show > Hidden items.
- Delete the remaining Paradox launcher folders in these locations if they exist:
%LOCALAPPDATA%ProgramsParadox Interactive,%LOCALAPPDATA%Paradox Interactive, and%APPDATA%Paradox Interactivelauncher-v2. Remove only the launcher-related folders, not unrelated save-game directories. - Restart Windows. This clears processes and file locks left by the old launcher.
- Re-create the antivirus and ransomware exceptions for Steam, the game,
bootstrapper.exeorbootstrapper-v2.exe, andparadoxlauncher.exebefore the first launch. - Run Steam as administrator and start the affected game. Steam should download and install the current launcher again.
If Windows reports that a folder is in use, restart once more and check Task Manager for remaining Paradox or Steam processes before trying the deletion again. Do not download a random launcher executable from a third-party site.
Reset launcher and game data safely
Use this branch when the launcher installs but remembers bad settings, shows stale game metadata, or repeatedly fails to load content. Back up custom configuration or save files first. Delete only the files listed below; they are cache and metadata, not the game’s core installation.
Files in a game’s data directory
For the affected game, open its Paradox data directory and remove .launcher-cache. Also remove the relevant content_load.json or dlc_load.json, game_data.json, and mods_registry.json files when present. You can remove the game’s mods folder as an additional reset, but doing so means you will need to download subscriptions again.
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Windows launcher settings
Remove the launcher-v2 settings left under your Windows AppData locations after closing Steam and the launcher. The residual locations are under %LOCALAPPDATA%Paradox Interactive and %APPDATA%Paradox Interactivelauncher-v2. Restart Windows before launching again so new databases are created cleanly.
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macOS settings
Close the game and launcher, then remove the Paradox launcher settings under ~/Library/Application Support/Paradox Interactive/. Keep personal saves and other game data unless the specific game support instructions tell you otherwise.
Linux settings
Close the launcher and remove its settings under ~/.paradoxlauncher and the listed Paradox directories under ~/.local/share/Paradox Interactive. Reopen Steam and let the launcher regenerate its files.
Repair missing mods and playsets
When the launcher opens but subscriptions, mods, or playsets are missing, Paradox identifies antivirus and ransomware protection as a frequent cause. Follow this sequence rather than immediately unsubscribing from everything.
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- Add the launcher and game executables to your antivirus exceptions, including
paradoxlauncher.exe, the appropriate bootstrapper, Steam, and the game’s executable. - Restart the launcher and check whether the existing playsets return.
- If they are still missing, exit Steam and the launcher. Unsubscribe from the affected mods in Steam Workshop so that stale entries are not immediately recreated.
- In the game’s data directory, delete the
modsfolder,mods_registry.json, andlauncher-v2.sqlite. The database filename can be in the launcher data location rather than beside the game’s executable; remove the copy associated with that game. - Start the launcher and subscribe to a small number of known-compatible mods first. Confirm that one test playset loads before resubscribing to a large collection.
If the test set works but a larger collection fails, add subscriptions in batches. That identifies a damaged or incompatible mod without forcing you to reset the entire library again.
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Resolve launcher JavaScript errors
A JavaScript error immediately after startup usually means the launcher installation or one of its Windows runtime dependencies is incomplete.
- Uninstall Paradox Launcher v2 from Windows Apps and Features.
- Restart Windows.
- Open Steam and start the game. Steam should install the current launcher again.
- If the same JavaScript error remains, install Microsoft’s latest supported Microsoft Visual C++ runtime bundle for your Windows architecture.
- Restart Windows once more and launch the game through Steam.
Use the current supported bundle from Microsoft rather than an old copy packaged on an unrelated download site. If the error text names a particular runtime component, include that exact text when contacting support.
When the launcher opens but the game will not start
Do not keep deleting launcher folders when the launcher itself runs normally. Paradox Helpdesk describes this situation as “almost certainly” a separate game or Windows problem.
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Test the game outside the launcher
- In Steam, choose Manage > Browse local files for the game.
- Run the main game executable directly. If it starts, the failure is in the Steam-to-launcher hand-off or a launcher setting; if it fails directly, concentrate on game files, drivers, Windows permissions, or game-specific logs.
- Return to Steam and use Properties > Installed Files > Verify integrity of game files to replace damaged game files.
- Temporarily remove custom launch options and test with the game’s default settings.
Keep graphics, audio, chipset, and other hardware drivers current when a direct launch produces a crash or a black screen. A driver problem belongs to the game or Windows troubleshooting path, not to a launcher-data reset.
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Check permissions and security blocks
Review Windows Security’s protection history again for the game executable, and make sure the account launching Steam can read and write the game’s folders. Re-enable any security feature you temporarily disabled after adding a precise exception.
Export logs before escalating
If none of the branches resolves the failure, provide support with evidence instead of a general “launcher does not work” description.
- Open the launcher, if it starts.
- Open Launcher Settings and choose Export Launcher Logs.
- Save the generated ZIP file without editing its contents.
- Submit it with a Paradox support ticket, the exact error text, your Windows, macOS, or Linux version, the affected game, and a screenshot when possible.
State which steps you completed, whether security software quarantined a file, and whether the game executable ran directly. Those details tell support whether to investigate the launcher, the game, or Windows.
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