SeleniumHQ/selenium · error · anyhow::Error

Unable to discover proper {} version in offline mode

Error message

Unable to discover proper {} version in offline mode

What it means

Produced by assert_online_or_err() using the OFFLINE_REQUEST_ERR_MSG constant ("Unable to discover proper {} version in offline mode"). It fires when Selenium Manager has detected offline mode but a manager's request_driver_version() needs the network (IEDriver, Edge, Firefox, Chrome, Grid, Electron). The placeholder is the driver name.

Source

Thrown at rust/src/lib.rs:1171

        let mut release_version = driver_version.to_string();
        if !driver_version.ends_with('0') && !self.is_nightly(driver_version) {
            // E.g.: version 4.8.1 is shipped within release 4.8.0
            let error_message = format!(
                "Wrong {} version: '{}'",
                self.get_driver_name(),
                driver_version
            );
            let index = release_version.rfind('.').ok_or(anyhow!(error_message))? + 1;
            release_version = release_version[..index].to_string();
            release_version.push('0');
        }
        Ok(format!("selenium-{release_version}"))
    }

    fn assert_online_or_err(&self, message: &str) -> Result<(), Error> {
        if self.is_offline() {
            return Err(anyhow!(format_one_arg(message, self.get_driver_name())));
        }
        Ok(())
    }

    fn get_driver_name_with_extension(&self) -> String {
        format!(
            "{}{}",
            self.get_driver_name(),
            get_binary_extension(self.get_os())
        )
    }

    fn get_browser_name_with_extension(&self) -> String {
        format!(
            "{}{}",
            self.get_browser_name(),
            get_binary_extension(self.get_os())
        )

View on GitHub (pinned to aa36b38e69)

Solutions

1. Allow network egress to the version-discovery endpoints (googlechromelabs.github.io, github.com, *githubusercontent.com, edge updates URLs).
2. Pre-populate the Selenium Manager cache with the needed driver so discovery can be served locally.
3. Pin the driver version via --driver-version so online discovery is bypassed.
4. Remove an explicit --offline flag if the host actually has connectivity.

Example fix

# before
selenium-manager --browser edge --offline   # cannot discover
# after (allow network, or pin)
selenium-manager --browser edge
curl -fsSL https://msedgedriver.azureedge.net/<ver>/edgedriver_<os>.zip -o ~/.cache/selenium/...

use std::net::ToSocketAddrs;
fn has_network() -> bool {
    "googlechromelabs.github.io:443".to_socket_addrs().is_ok()
}
// guard before relying on online discovery
if !has_network() {
    eprintln!("offline: pin a driver version or seed the cache");
}

When it happens

Trigger: is_offline() is true and a browser manager calls self.assert_online_or_err(OFFLINE_REQUEST_ERR_MSG) inside request_driver_version() (see iexplorer.rs:140, edge.rs:245, firefox.rs:241, chrome.rs:345, grid.rs:128, electron.rs:184).

Common situations: Air-gapped CI; --offline flag set; no default route detected; DNS resolution failing so Selenium Manager treats the host as offline; corporate firewall blocks the version endpoints.

Related errors

• The {} version cannot be discovered
• Unable to download {} in offline mode
• Unable to obtain browser driver. For more informatio
• Error executing command for ${smBinary} with ${args}: ${erro
• Unsuccessful command executed: {command}; code: {completed_p

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/86c6bfae434e9501. Report an issue: GitHub.