Massive Windows 11 Bug Can Eat Up to 70 GB of C: What’s Happening and How to Fix It

Some users notice that their C: drive loses tens of gigabytes despite not downloading large files. The root cause is a severe disk‑space bug in Windows 11 that silently expands a SQLite write‑ahead log file.

The culprit is the default service called Capability Access Manager, which manages permission requests for UWP apps. During normal operation it creates a file named CapabilityAccessManager.db-wal. Under the bug’s influence this WAL file can grow from a few kilobytes to 70‑80 GB, and in extreme cases up to 500 GB, completely filling the system partition.

The problem was first reported by users on Microsoft’s official support forum. Initially Microsoft’s support team could not identify the issue or provide a sensible solution. After several months of investigation, Microsoft pinpointed the cause and delivered a fix in the June cumulative update KB5095093, noting in the release notes that the update improves the disk‑space usage of the CapabilityAccessManager.db-wal file.

Although the patch stops further uncontrolled growth, Microsoft did not disclose the exact technical reason for the file’s expansion. Independent investigations suggest that third‑party utilities such as Rainmeter, which frequently request location or network status, may generate excessive write traffic that fills the WAL. Windows lacks a mechanism to monitor and limit the size of this log, leading to unnecessary SSD wear and degraded system performance.

To resolve the issue, users should promptly install KB5095093 or any newer Windows Update that contains the fix. For systems where the C: drive is already saturated, the recommended manual remedy is to boot into Safe Mode, delete the oversized CapabilityAccessManager.db-wal file, and then restart; Windows will recreate a correctly sized file automatically.

Have you experienced a similar “mysterious” loss of C: drive space?