WinSCP 6.6.4 RC has been available since 7 October 2026. For Windows administrators investigating reproducible problems, this is a reason for a controlled test, not an unverified replacement of every installation. This guide keeps production connections, files and test settings separate.
What changed, and what RC means
The download page lists 6.6.4 RC as a prerelease alongside 6.5.7 in the regular 6.5 branch. The version history dates the release to 7 October. [1][2] Issue 2462 concerns crashes or unexpected behaviour when a saved site and workspace have the same name; Issue 2458 concerns a WinSCP process remaining after opening PuTTY. The vendor marks both as fixed in 6.6.4. This does not mean every installation is affected. [5][6]
Requirements and backup
You need an approved Windows test machine, a writable local test folder and, if necessary, a test server with a restricted account. Record the existing version and installation type. Back up the configuration using Tools → Export/Backup configuration in the Login dialog. The export may contain sensitive connection information: store it securely, not in tickets or chats. Private keys and server files need their own protected recovery path. [3]
Five steps to check
- Define the goal: record the exact symptom, action and expected result. If you have no relevant issue to investigate, the availability of an RC alone is not a reason to replace an approved production installation.
- Choose the package: visit the official download page and deliberately select the portable 6.6.4 RC edition. Extract it into a new test folder without overwriting existing program files. Portable use is intended for experienced users and does not automatically provide complete isolation. [2][4]
- Separate settings explicitly: from the test folder, start WinSCP.exe /ini=nul. WinSCP then uses defaults and does not save configuration on exit. This is not a sandbox and does not prevent file or server changes. Do not import production sites. Tests requiring saved settings instead need a separate test INI as described in the vendor documentation. [3]
- Use test data only: check the host and destination before connecting. Independently verify a new or changed SSH host key with the operator instead of accepting it blindly. A harmless file in a specifically approved test folder is sufficient for a transfer check. Do not start automatic synchronization, deletion or editing of production files.
- Check the outcome: when testing Issue 2458, finish transfers, close WinSCP normally and check in Task Manager whether its process exits. Do not force active processes to terminate. For Issue 2462, use invented names only in the separate test configuration. Also check transferred test files for content and size; establishing a connection alone is not success. [5][6]
Stop when results differ
Stop on a wrong destination, unexpected key, crash or content mismatch. Record the version, Windows version, installation type and anonymized reproduction steps. Do not publish passwords, keys, full configurations or confidential filenames. One successful test does not approve every script, protocol or server.
Success and a way back
Success means the predefined workflow works with test data and production remains unchanged. To go back, close the RC normally and resume using the previously approved application with its original settings. Do not import the separate RC configuration over production settings. Switching applications cannot restore server files already changed; that requires the separate data backup.
Date and sources
As of 8 October 2026. Source-based guidance, not our own WinSCP installation test or independently reproduced fix. Selected for its documented release, not a proven version-specific search surge. No affiliate links.