Network errors (net::ERR_QUIC_PROTOCOL_ERROR, "Network error calling …")

Connection drops between your computer and Microsoft 365. The app retries; if a few files still fail, run the task again.

What it means

The connection to SharePoint or Google broke during a request: a VPN or proxy dropped it, Wi-Fi was interrupted, or a firewall inspecting traffic reset it. ERR_QUIC_PROTOCOL_ERROR comes from QUIC (HTTP/3), which some firewalls and proxies don't handle.

The app retries dropped connections and restarts an interrupted upload from the beginning. Current versions turn QUIC off, so traffic uses ordinary HTTPS.

How to fix it

1. Update the app to the latest version.
2. Run again with Copy if newer (incremental) – only the failed files are copied.
3. If many files fail:

• Use a wired connection, or pause the VPN if your policy allows.
• Ask your network team to allow *.sharepoint.com, login.microsoftonline.com and *.googleapis.com without TLS inspection.
• Lower the Run … at a time number on the Tasks page so fewer uploads share the connection.

Updated 2026-10-26