View Optical Drive Class Filters in Regedit

This article explains how to locate and inspect the active device setup class filters for optical disk drives using the Windows Registry Editor (Regedit). Corrupted or conflicting class filters—specifically UpperFilters and LowerFilters—are common causes of CD, DVD, and Blu-ray drive errors in Windows. Finding these values allows administrators and users to identify which filter drivers are actively attached to the optical drive class stack.

Optical Drive Setup Class Registry Path

To view the active device setup class filters for CD-ROM, DVD, and Blu-ray drives, navigate to the following path in the Windows Registry Editor:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e965-e325-11ce-bfc1-08002be10318}

The Globally Unique Identifier (GUID) {4d36e965-e325-11ce-bfc1-08002be10318} represents the standard Windows device setup class for CD/DVD/Blu-ray drives (CDROM).

How to Access and View the Filters

  1. Press Windows Key + R, type regedit, and press Enter to open the Registry Editor.
  2. In the left navigation pane, expand the folders to follow the path: HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Control > Class
  3. Click on the {4d36e965-e325-11ce-bfc1-08002be10318} key.
  4. Look at the right-hand details pane for two multi-string values (REG_MULTI_SZ):
    • UpperFilters: Lists filter drivers loaded above the class driver in the device stack.
    • LowerFilters: Lists filter drivers loaded below the class driver in the device stack.

Interpreting the Values

If third-party disc burning, virtual drive, or backup software has modified your optical drive stack, their respective driver names (such as GEARAspiWDM or PxHlpa64) will appear inside the UpperFilters or LowerFilters entries. If neither value is present in the right pane, the optical drive class is running using only standard, built-in Windows drivers without any active third-party class filters.