Can't start LB, problem related to Steam storefront

[AliMujahid20]

Hello, guys!

I had the misfortune of one of my PC hard drives failing over the weekend, and I was only able to recover 75% of the games that were on it (Steam, 4 from Epic, and 1 from Ubisoft). After recovering my hard drive (after formatting it) and adding all the content I had saved, I could no longer access LaunchBox (which is in another hard disk btw) because an error message appeared (I have attached the complete log). I deleted the LB folder and reinstalled the programme, skipping all the processes (loading the games folder, downloading metadata, logging into the LB Database and Retroachievements, and above all logging into stores such as Steam or Epic). When I entered LB, I logged into one of the storefronts where my accounts are linked to Steam (yes, you can log into Epic and Ubisoft via Steam, which is my case). When I did this, the following error message reappeared after start LB again:

What should I do? Please, I need help as I have been trying to fix and reinstall LB for several days but I can't seem to get it right.

Debug 2025-12-30 06-47-18 PM.log

Edited December 31, 2025 by AliMujahid20

[AliMujahid20]

Happy new year 2026!

Hi everyone,
I wanted to share the solution to a persistent crash I encountered in LaunchBox 13.24. Even when I tried to add non-Steam platforms, the app would crash on startup with the following error:

minimumLength ('-2147483064') must be a non-negative value. (Parameter 'minimumLength')

The Fix:
The issue was caused by a corrupted Steam configuration file. To fix it, I had to:

1. Close LaunchBox and Steam completely.
2. Go to C:\Program Files (x86)\Steam\steamapps\ and delete/rename libraryfolders.vdf.
3. Go to C:\Program Files (x86)\Steam\config\ and delete libraryfolders.vdf there as well.
4. Restart Steam (it will recreate these files, though you may need to "Install" your games again for Steam to rediscover the existing files).
5. Open LaunchBox.

The Explanation:
The crash happens because LaunchBox 13.x uses .NET 9, which is much stricter regarding memory allocation and string handling. In my case, the libraryfolders.vdf file in Steam was corrupted, containing a "garbage" value (the negative integer -2147483064).
When LaunchBox initialized its background storefront services (even if I wasn't importing Steam games at that moment), it called Unbroken.LaunchBox.Windows.Integrations.Steam.GetInstalledAppIds(). This method attempted to read the corrupted Steam file. Because the file provided an invalid/negative string length, the .NET runtime (System.Private.CoreLib) threw an ArgumentOutOfRangeException and forced the app to close to prevent memory corruption.
By deleting the .vdf files, I forced Steam to regenerate a clean, properly formatted database. This allowed LaunchBox to successfully parse the Steam integration data without hitting the invalid buffer size error.
Hopefully, this helps anyone else seeing this specific "minimumLength" error!

Credits: Gemini AI by Google. 🤓

UPDATE: This was a temporal solution but the real problem and how to solve it is in the next post!

Edited yesterday at 10:47 AM by AliMujahid20

[AliMujahid20]

UPDATE: Issue Resolved – Root Cause Found (Corrupted Steam .TMP files)
I finally managed to fix the crash! Even after cleaning my main Steam installation, the error returned as soon as I re-added my secondary library (Drive E:), which contains over 1TB of games and had recently suffered a hardware/file system error.

The Culprit:
The crash was caused by leftover temporary manifest files in the SteamLibrary\steamapps\ folder. In my case, I found 195 files with extensions like .acf.tmp or appmanifest_xxxxx.acf.xxxx.
When a disk failure occurs during a Steam update, Steam leaves these partial "shadow" files behind. While Steam itself ignores them, LaunchBox’s startup scan (specifically the GetInstalledAppIds method) appears to attempt to parse any file beginning with "appmanifest". Because these .tmp files contain binary "garbage" or null characters instead of proper text, the .NET 9 runtime in LaunchBox 13.24 fails to calculate the string length, triggering the error

ArgumentOutOfRangeException: minimumLength ('-2147483064')

How to Fix:
If you have a large library and LaunchBox crashes only when your Steam drive is connected:

1. Go to your Steam library folder (e.g., E:\SteamLibrary\steamapps\).
2. Search for *.acf.* or look for any file that does not end exactly in .acf.
3. Delete all files ending in .tmp or ending with a string of numbers (e.g., appmanifest_12345.acf.6789).
4. Ensure only the clean .acf files remain.
5. Also, clear the steamapps\downloading folder on that drive, as it may contain similar corrupted data.

Once I deleted those 195 corrupted temporary files, LaunchBox opened instantly without any errors, and all my platforms loaded perfectly.

Conclusion:
If your drive has ever had a "dirty" shutdown or a disk error, check for these hidden .tmp manifest files. .NET 9 is extremely sensitive to the malformed data inside them, and cleaning them up is the only way to stop the crash.

 

Once again, thanks to Gemini AI by Google. 😇

Edited yesterday at 10:48 AM by AliMujahid20