PLA_E_TOO_MANY_FOLDERS (0x80300045): Quick Fix for Data Collector Set

Quick answer: Delete old subfolders under %SystemRoot%\System32\LogFiles\WMI\RtBackup or increase the folder limit in the registry.

You're running a Data Collector Set in Performance Monitor, maybe for a scheduled trace or a network capture. Then you get this: Unable to start Data Collector Set because there are too many folders. The error code is 0x80300045. It's not common, but when it hits, it stops everything.

Had a client last month whose nightly performance logs stopped writing for two weeks. They blamed the server, rebuilt it, wasted hours. The real culprit? The WMI trace folder had 10,000+ subfolders from old traces. Windows has a hard limit of 9,999 subfolders in that directory. Once crossed, no new Data Collector Sets can start. The fix is simple: clean house or raise the cap.

Main Fix: Delete Old Trace Folders

This is the fastest way. The error is almost always caused by accumulated trace subfolders in the WMI log path.

1. Open File Explorer and paste this path into the address bar (run as Admin if you can):
   %SystemRoot%\System32\LogFiles\WMI\RtBackup
2. You'll see a ton of subfolders named like Trace_2025_03_15_10_30_45 or similar. Select them all (Ctrl+A) and delete. If you get a permission error, take ownership first or use a command prompt as Admin.
3. Empty the Recycle Bin.
4. Restart the Data Collector Set in PerfMon or restart the Performance Logs & Alerts service (pla in services.msc).

That's it. The error should clear. I've seen this work on Windows 10, 11, Server 2016, and 2019. The limit is hard-coded at 9,999 subfolders. Once you're below that, it starts again.

Alternative Fix: Increase the Folder Limit via Registry

If you can't delete folders (locked by a process, or you just want to keep historical data), you can raise the limit. This is riskier, so back up the registry first.

1. Open Registry Editor (regedit.exe) as Administrator.
2. Navigate to:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WMI\AutoLogger
3. Look for a DWORD named MaxFileCount. If it's not there, create it (DWORD 32-bit).
4. Set its value to something higher than 9,999. I usually set it to 20000 (decimal). Don't go crazy—50000 might cause other issues.
5. Restart the machine or the Windows Event Log service.

This raises the subfolder cap. Test by starting the Data Collector Set again. I've used this on a client's server where they needed to keep 6 months of traces for compliance. It worked, but I still recommend cleaning old folders periodically.

Alternative Fix: Delete Through Command Line

If the GUI gives you trouble with permissions or number of files, use this PowerShell one-liner. Open PowerShell as Admin and run:

Remove-Item -Path "$env:SystemRoot\System32\LogFiles\WMI\RtBackup\*" -Recurse -Force

This nukes all subfolders. Be careful—no undo. But it's reliable. Had a case where the folder had 12,000+ items and Explorer choked. PowerShell handled it in 30 seconds.

Prevention Tip: Schedule a Cleanup

Once you've cleared the error, set up a scheduled task to delete old folders. Use this script in Task Scheduler, running weekly:

Get-ChildItem -Path "$env:SystemRoot\System32\LogFiles\WMI\RtBackup" | Where-Object { $_.CreationTime -lt (Get-Date).AddDays(-30) } | Remove-Item -Recurse -Force

This removes folders older than 30 days. Adjust the days to match your retention needs. I do this on every server I touch now. It's saved me calls at 2 AM.

What Causes This in the Real World?

Most commonly, I see it from:

• Long-running Data Collector Sets that create a new folder per session (e.g., every 15 minutes for months).
• Windows Performance Recorder (WPR) traces left running unattended.
• Third-party monitoring tools that create WMI-based traces and never clean up.
• One client had a misconfigured SQL trace that dumped a new folder every 5 minutes. 2,880 folders a day. Hit the limit in under 4 days.

The error itself is exact: PLA_E_TOO_MANY_FOLDERS means the folder count hit 9,999. Nothing subtle about it.

When to Skip the Registry Fix

Don't raise the folder limit if you're low on disk space. Those trace folders can eat gigabytes. I'd rather delete old ones than let them pile up. The registry fix is a band-aid—not a strategy.

Also, if you're on Windows 10 Home, the registry key might not exist. Create it, but test carefully. No guarantees.

Bottom line: delete the old folders first. It's safe, fast, and solves the problem. Only touch the registry if you absolutely must keep every trace.