#2548·capnproto

Does not compile on exFAT drive

Author: muhunaCreated Feb 2, 2026Updated Feb 2, 2026

The library does not compile when the source code is on a drive formatted with exFAT. This error is repeatable, i.e. when changing to NTFS compiling works, switching back to exFAT breaks it. Visual Studio 2019 gives the following error:

kj\filesystem-disk-win32.c++:373: failed: GetFileInformationByHandleEx(FileCompressionInfo): #87 The parameter is incorrect.

According to google "This error occurs because a program (often related to Cap'n Proto or similar libraries) is trying to check the compression status of a file using Windows' GetFileInformationByHandleEx API, but the underlying filesystem (e.g., a network drive, virtual drive, or non-NTFS drive) or the specific file handle does not support the FileCompressionInfo parameter."