When Monosnap’s SFTP upload stops working
Usually it worked for years, then one day it didn’t — no error, no upload, just a silent failure. Here’s why it’s happening across the board in 2026, and what to do about it.
$ press Ctrl+Alt+7 > region captured ok > annotate ok > upload ... > upload ... > upload connection closed (no error) > clipboard URL — never populated
Why SFTP broke
Two things changed in the hosting industry over the last couple of years. First, most reputable hosts disabled the SHA-1 RSA key algorithm by default because SHA-1 is no longer considered secure. Second, many hosts now require Ed25519 keys or at least SHA-2 (rsa-sha2-256 / rsa-sha2-512) on RSA. A lot of long-running SFTP clients never updated their SSH libraries to support these, so connections that worked fine in 2022 just stop working after a host's upgrade rollout.
Monosnap's SSH library has not kept pace. Users on recent threads report the same pattern: upload attempts hang for several seconds, then the connection is closed with no surfaced error. Sometimes the editor shows "upload failed" after a timeout; often it shows nothing at all.
What works
Maxisnap ships with an updated Paramiko SSH library that supports Ed25519, ECDSA-P256/P384/P521, and both SHA-1 and SHA-2 RSA. It will negotiate the strongest algorithm your server accepts. It also releases sockets and transport objects in finally blocks, so a failed upload doesn't leak a file descriptor — one of the other silent causes of "it worked for a while then stopped" in long-running sessions.
Migrating is straightforward. Open Settings → Upload → Add Server. Pick SFTP. Paste the same host, port, username, password or private key path, remote directory, and public-facing base URL. Click Test. Done.
Which protocols work, which don’t
| Protocol / Feature | Monosnap (2026) | Maxisnap v2.1.5 |
|---|---|---|
| SFTP with RSA SHA-1 | Works | Works |
| SFTP with RSA SHA-2 | Inconsistent | Works |
| SFTP with Ed25519 | Broken | Works |
| SFTP with ECDSA | Broken | Works |
| FTP (plain) | Works | Works |
| FTPS (TLS) | Partial | Works |
| Amazon S3 | Works | Works |
| S3-compatible (R2 / B2) | Unclear | Works |
| Custom HTTP POST | Works | Works |
| Connection released on error | Leaks socket | finally block |
Move your server config in 60 seconds
Export your Monosnap settings for reference
Open Monosnap Preferences → Upload and jot down: host, port, username, key path or password, remote path, base URL.
Install Maxisnap
Grab the installer. Free, 63 MB, Windows 10/11.
Add the server in Maxisnap
Settings → Upload → Add Server → SFTP. Paste the fields you noted. Click Test Connection.
Set it as active
Mark your new SFTP server active and hit Ctrl+Alt+7 to capture and upload. Your clipboard gets the URL.
SFTP questions
My Ed25519 key is in OpenSSH format. Will it load?
Yes. Maxisnap reads OpenSSH and PEM formats. If your key is password-protected, you’ll be prompted once per session for the passphrase.
Does Maxisnap honor my ~/.ssh/config?
Not currently. You configure each server explicitly in Maxisnap’s Upload dialog. This makes the config portable and independent of your OpenSSH setup.
Can I switch upload destinations per screenshot?
Yes. Right-click the tray icon while an editor is open, or use the server dropdown in the editor toolbar to pick a different server for a one-off upload.
SFTP that actually uploads
Modern key algorithms, proper error handling, free to try.
Download MaxisnapRelated: general alternative · leaving Monosnap · 2-minute switch