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Epic Games’ prerequisite errors usually indicate that Windows could not run a required installer with the permissions or runtime components it needed. SU-PQR1603 occurs while the Epic Games Launcher is updating itself; LS-0019 (often shown as LS-0019-IS-PQR1638) occurs when a game is launching and its prerequisite installer fails. Restart Windows, run the launcher with administrator rights, verify Read and Write access to the install folder, update the launcher, and repair the required Visual C++/DirectX/.NET components in that order. Use -SkipBuildPatchPrereq only as a temporary workaround, then remove it.
What do SU-PQR1603 and LS-0019 mean?
These codes describe a prerequisite-installation failure, not proof that the game’s main files are corrupted. The stage at which the message appears tells you which component to investigate.
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| Error | Typical message | Failure stage | What it points to |
|---|---|---|---|
| SU-PQR1603 | “Self Update Failed / The necessary prerequisites failed to install. Please contact support. / Error Code: SU-PQR1603.” | Epic Games Launcher self-update | The launcher could not complete a prerequisite step needed for its own update. |
| LS-0019-IS-PQR1638 (often shortened to LS-0019) | “Launch Failed / The prerequisites for <game-name> failed to install. / Error Code: LS-0019-IS-PQR1638.” | Game launch | The game’s prerequisite installer did not finish before launch. |
The two messages look similar because both involve prerequisites, but they are not interchangeable. If the launcher itself says “Self Update Failed,” concentrate first on launcher elevation, update state and folder access. If a particular game says “Launch Failed,” check the game’s install location and the Windows runtimes it requests.
Which Windows systems and causes are covered?
The troubleshooting guidance for these messages concerns Epic Games Launcher installations on Windows 10 and Windows 11 PCs. How-to sources associate the failures with insufficient administrator elevation, missing Read/Write permission on the intended install folder, an outdated or interrupted launcher update, and damaged or incomplete runtime components. Those are plausible causes rather than a vendor-published list that makes one cause universal.
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- Elevation: Windows may block a prerequisite installer that needs to write to protected locations unless the launcher is elevated.
- Folder access: The account running Epic Games Launcher must be able to read and write the destination folder.
- Launcher state: A pending, failed or incomplete launcher update can leave the prerequisite stage unable to proceed.
- Runtime components: Microsoft Visual C++ Redistributables are repeatedly identified in troubleshooting guidance; DirectX and .NET Framework are also listed as prerequisite components that may need repair.
There is no measured success rate for any individual remedy in the available guidance. Treat the sequence below as a low-risk diagnostic order, not a guarantee that one step fixes every installation.
How can I identify the correct repair path?
Note the exact code and when it appears before changing anything. This prevents applying a game-launch fix to a launcher self-update problem.
- Write down whether the message appears immediately when Epic Games Launcher opens, while it says it is updating, or only after you select a game.
- Record the complete code, including the
-IS-PQR1638suffix if it is displayed. - Note your Windows version and, if the launcher opens, its version from the launcher’s settings or about information.
- For LS-0019, record the affected game and its installation folder. If only one game fails, start with that folder’s permissions and prerequisites.
Do not delete the game directory at this stage. The codes concern prerequisite execution and permissions; deleting files can create a separate download or verification problem.
What should I try first when prerequisites fail?
1. Restart Windows
Use Start > Power > Restart, wait for Windows to sign in completely, and try the launcher again. A restart clears an installer process or pending update state that did not close cleanly.
2. Run Epic Games Launcher as administrator
Right-click the Epic Games Launcher shortcut and choose Run as administrator. Approve the Windows permission prompt, then retry the update or game launch.
If this works and you want the launcher to request elevation every time, right-click the shortcut, choose Properties, open the Compatibility tab, select Run this program as an administrator, choose Apply, and then OK. Persistent elevation changes how the launcher starts, so use it only on the Windows account where you need it.
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3. Check the install folder’s Read and Write permissions
Locate the folder where the affected game is installed, or the folder selected for a new installation. Right-click it and choose Properties, open Security, select your Windows user account, and look at the permissions list.
- Confirm that Read and Write are allowed.
- If either permission is missing, choose Edit, select the account, allow the required permissions, and apply the change.
- Retry Epic Games Launcher as administrator after the change.
If you cannot edit the permissions because the account is not permitted to change them, stop rather than taking ownership of unrelated system folders. Ask the owner of the PC or its administrator to make the narrowly scoped change on the game’s intended folder.
How do I update the Epic Games Launcher after a failed prerequisite check?
When the launcher can open, use its built-in update command rather than repeatedly launching a stale copy.
- Open the profile menu in the upper-right area of Epic Games Launcher.
- Choose Settings.
- If an update is available, choose Restart and Update.
- Allow the launcher to close and restart, then test the original operation again.
If the launcher never reaches its interface and only displays SU-PQR1603, complete the restart, administrator and folder checks first. A failed self-update can prevent the settings screen from being available.
Which prerequisite runtimes should I repair?
Windows games commonly rely on redistributable runtime packages. The troubleshooting sources specifically call out Microsoft Visual C++ Redistributables and also list DirectX and .NET Framework as components that may be missing or damaged.
Microsoft Visual C++ Redistributables
Use the installed-apps list in Windows to look for Microsoft Visual C++ Redistributable entries. If an entry offers a Modify or Repair action, use that option; otherwise install the appropriate current package from Microsoft’s official distribution channel. Restart Windows after repairing or reinstalling, then run Epic Games Launcher as administrator and retry.
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Keep both the x86 and x64 variants if they are already installed. Different games can depend on different architectures, so removing one merely because another is present can create a new launch failure.
DirectX
If the game’s prerequisite process mentions DirectX or the installation remains incomplete after Visual C++ repair, install or repair the DirectX component using Microsoft’s official installer. Do not download a “DirectX fix” from an unverified mirror.
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.NET Framework
Install or repair the .NET Framework version required by the game or launcher, again using Microsoft’s official distribution channel. Windows may require a restart before the repaired component is available to the prerequisite installer.
The cited troubleshooting articles do not establish that any one runtime is the cause in every case. Repair only the components you need, and avoid removing unrelated runtimes from Windows.
Can -SkipBuildPatchPrereq bypass the error?
It can bypass a faulty prerequisite check in some Epic Games Launcher installations, but it is a workaround rather than a repair. The Windows Club describes the flag as a workaround, and other guidance warns that leaving it enabled can affect later launcher self-updates.
- Close Epic Games Launcher completely.
- Right-click the Epic Games Launcher shortcut and choose Properties.
- In the Shortcut tab, click the Target field and place the cursor at the end of the existing text.
- Type one space, then
-SkipBuildPatchPrereq. Do not remove the existing executable path or its quotation marks. - Choose Apply, then OK.
- Start the launcher from that shortcut, preferably with Run as administrator, and test the update or game launch.
After the immediate task succeeds, close the launcher, remove the added flag from the shortcut’s Target field, apply the change, and start the launcher normally. The flag does not repair a missing runtime, grant folder permissions or restore corrupted game files; it only skips the prerequisite check that is blocking startup.
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Which remedy should I choose?
| Remedy | Primary stage | Privilege or dependency addressed | Reversibility | Risk and trade-off |
|---|---|---|---|---|
| Restart Windows | Both | Clears a stuck installer or pending state | Immediate | Very low risk; may not change a persistent permission problem. |
| Run launcher as administrator | Both | Elevation needed by the launcher or prerequisite installer | Immediate, or persistent through Compatibility settings | Low risk when limited to the launcher; persistent elevation changes its startup behavior. |
| Grant Read and Write on the intended folder | Usually game launch, also installs | Folder access control | Reversible in the Security tab | Keep the change scoped to the game folder; do not alter unrelated system directories. |
| Restart and Update | Launcher self-update | Outdated or incomplete launcher update | Launcher-managed | Low risk; unavailable if the launcher cannot open. |
| Repair Visual C++/DirectX/.NET | Game launch and some launcher prerequisites | Missing or damaged runtimes | Repair or uninstall can be reversed by reinstalling | Use publisher installers and avoid deleting runtimes indiscriminately. |
-SkipBuildPatchPrereq |
Launcher startup or update check | Skips the prerequisite gate | Remove the shortcut argument | Temporary workaround; may interfere with future self-updates and does not fix the underlying dependency. |
What if SU-PQR1603 still appears?
Because SU-PQR1603 is tied to the launcher’s self-update prerequisite stage, work through the sequence without jumping straight to game-file deletion:
- Restart Windows once more and confirm the launcher is fully closed before reopening it.
- Use the persistent Compatibility > Run this program as an administrator setting, then retry.
- Check Read and Write access on the folder where the launcher or its update data is intended to write.
- If the interface opens, use Profile menu > Settings > Restart and Update.
- Repair the Visual C++ runtime and, when indicated, DirectX or .NET Framework.
- Use
-SkipBuildPatchPrereqonly to get past the blocked check, and remove it after testing.
If the launcher cannot update even after these checks, capture the exact message and launcher version before contacting Epic support. A support request is more actionable when it identifies SU-PQR1603 as a self-update failure rather than simply saying that a game will not start.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What if LS-0019 appears for only one game?
LS-0019 points to a game-launch prerequisite installer. Start with the affected game’s destination folder, then check the runtimes that game may require.
- Confirm the Windows account running Epic Games Launcher has Read and Write permission on that game’s install folder.
- Run the launcher as administrator and launch the game again.
- Repair Visual C++ Redistributables; if the prerequisite dialog identifies them, repair the matching package rather than removing other versions.
- Repair or install DirectX and .NET Framework when the game’s prerequisite process requests them or when the runtime repair is otherwise indicated.
- Record whether other games launch normally. A single-game failure narrows the scope to that game’s folder or prerequisite set, while failures across games point more strongly to launcher permissions or shared runtimes.
Do not treat LS-0019 alone as evidence that the game’s content files are damaged. The documented message says the prerequisite installer failed; it does not identify a corrupt data file.
When should I contact Epic support?
Escalate after the restart, elevation, permission, launcher-update and runtime checks fail, or when Windows will not let you make the required permission change. Include details that distinguish the two code families.
- The exact error text and complete code, including
LS-0019-IS-PQR1638if shown. - Windows 10 or Windows 11 and the launcher version.
- Whether the failure occurs during launcher self-update or while launching a named game.
- The install-folder path and whether Read and Write were allowed for your account.
- Which runtime repairs were attempted and whether the shortcut flag was tested and then removed.
No current code-specific Epic support response time is established by the available guidance, so avoid relying on a promised turnaround. Keep the original error screenshot or copied text until support has finished diagnosing the installation.
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Do I need to buy hardware or delete the game?
No. The documented remedies concern Windows permissions, launcher state and software runtimes; they do not require a physical product or accessory. Buying a generic PC component would not address the cited causes, and deleting the game can turn a prerequisite problem into a lengthy re-download without proving that the data was defective.
How can I prevent the error from returning?
- Remove
-SkipBuildPatchPrereqonce troubleshooting is complete so normal launcher update checks can run. - Keep the launcher and Windows runtimes current through their publishers’ installers.
- Install games into a folder where your account has the required Read and Write access, rather than changing permissions broadly across the system.
- When an update is offered, let the launcher finish and restart before launching a game.
- Save the exact code and stage if the message recurs; SU-PQR1603 and LS-0019 require different first checks.
Frequently Asked Questions
Will fixing these errors uninstall my Epic Games library?
The listed steps do not require uninstalling games or the launcher. Restarting, changing a folder permission, repairing a runtime and removing a shortcut argument leave existing game data in place; avoid deleting folders unless Epic support specifically instructs you to do so.
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The flag only skips the prerequisite gate for that launch. If the underlying permission or runtime problem remains, normal startup can show the original code again, so use the flag as a diagnostic bridge while repairing the dependency rather than as a permanent setting.
Can a standard Windows account fix LS-0019?
You can inspect the game folder and launch the client, but changing its Security permissions or installing system runtimes may require an administrator account. Ask the PC administrator to perform those narrowly scoped actions instead of weakening permissions globally.
Is LS-0019 the same as a failed game-file verification?
No. LS-0019 identifies a prerequisite installer that did not complete before launch. File verification addresses damaged or missing game content, which this code by itself does not establish as the cause.
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