Hello,
I would like to report a possible memory management issue in WinSCP 6.7 ((Build 17845 2026-10-14) on Windows 11 Pro 25H2 64-bit when uploading large files (about 15 GB/file x 70 files = 1,050 GB) to Amazon S3.
After upgrading from WinSCP 6.5.7 to 6.7, I started experiencing several memory-related errors during S3 operations. These problems did not occur with version 6.5.7.
- SSL handshake failure during file uploads
When uploading a large file to Amazon S3, the transfer initially proceeds but eventually fails with the following error:
SSL handshake failed: SSL error: malloc failure
- Out of memory during file list retrieval
An Out of memory error also occurs while WinSCP is retrieving or preparing the list of files to transfer, even when uploading only a single large file.
When using WinSCP 6.5.7, the upload completed successfully without any of the errors described above.
This suggests that the issue may have been introduced in WinSCP 6.7.
Is this a known issue in WinSCP 6.7?
Have there been any changes in memory management or SSL/TLS handling that could explain these symptoms?
Thank you for your assistance.