I've noticed with another tool, and confirmed with a recent sqlite3.exe shell running on Windows 10 64-bit, (which starts by saying "SQLite version 3.31.1 2020-01-27 19:55:54"), that the .load command will fail when the provided FILE argument contains backslash as the path component separator. Since the OS itself is agnostic as to whether '/' or '\\' separates path components, this pickiness seems unfortunate. (I always consider it a win when a problem can be cured simply by removing stuff.) Since I can see no code in shell.c which effects such pickiness, I assume it is in either the SQLite3 library code or the VFS code for Windows. Perhaps that can be simplified since I see numerous clauses endeavoring to use the "right" separator. The SQL function load_extension(...) suffers the same issue, of course. It's not a huge problem since '/' works fine, but it is an inconvenience when paths are copied and pasted because the '\\' separator is ubiquitous on Windows.