Are you passing a Unicode pathname to sqlite3_open()? Maybe you need to call [sqlite3_open16()](https://sqlite.org/c3ref/open.html). Or, if you're calling sqlite3_open_v2(), a [WideCharToMultiByte()](https://docs.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-widechartomultibyte) conversion may be needed.