Fix a Stuck or Failed Browser Download

The first time a profile uses a browser version, MaskPilot prepares that version on the current device before launching the profile. If the download or installation does not complete, the launch stops instead of treating incomplete files as a usable browser.

Identify the stage that failed

The client progress panel shows the current step. Each stage points to a different cause:

• Preparing browser download: the client is obtaining version information for the current device. If this fails, confirm that the client is still signed in and can reach MaskPilot services.
• Downloading browser: the client is transferring the file. A percentage appears only when the server provides the total file size. No percentage does not mean the download is stuck if the transferred byte count is still changing.
• Verifying browser files: the download has finished and the client is checking file integrity. A failed verification does not proceed to installation.
• Installing browser: the client is extracting and preparing the executable locally. This stage depends mainly on free disk space, security software, and local file access.
• Starting browser: the browser files are ready. A failure after this point is not necessarily a download problem; check the proxy, extensions, and profile launch conditions too.

Record the last stage and the complete error shown on the page before retrying. Do not judge the state only by whether the progress bar has a percentage.

If the download stops or fails

Work through these checks in order:

1. Confirm that the device has a stable connection. Temporarily remove a VPN, corporate proxy, or network filter that changes the download path, then retry.
2. Check that the system drive has enough free space for both the downloaded archive and the extracted browser directory.
3. Check whether a firewall or security product blocked MaskPilot from downloading or writing local files. Allow only the trusted MaskPilot client instead of disabling protection globally.
4. Open Updates → Browser version, find the version selected by the profile, and download it again.
5. Do not repeatedly launch several profiles while the same version is downloading. The client coordinates requests for one version, and waiting launches can reuse the verified build after the first task finishes.

A failed temporary download is not marked as installed. Retry from the client after the connection recovers rather than copying an incomplete file into the browser directory.

If verification or installation fails

When the file has downloaded but verification or installation fails:

1. Keep the original error and do not substitute a browser archive from an untrusted source.
2. Confirm that the system clock is correct, enough disk space is available, and the security product has not quarantined or blocked the file.
3. Return to Browser version and download the same version again so the client can verify and install a fresh copy.
4. If one version fails repeatedly while another completes, record the failed browser version and current client version before contacting support.

MaskPilot verifies the downloaded file before installation. Stopping on a failed integrity check is safer than running a damaged or mismatched file.

If the download completes but the profile still will not launch

Once progress reaches Starting browser or Browser version shows Downloaded, another download usually will not fix a later failure. If the page explicitly says “Preflight check failed,” start with the preflight troubleshooting checklist. Otherwise, check these areas separately:

• Confirm that the assigned proxy and its complete upstream route pass validation; see fix a profile that will not start with a proxy.
• Confirm that each selected extension supports the browser version; see extension disabled after a browser update.
• Check for an existing local process or launch operation, and confirm that you use a current, compatible client; see why a profile says it is in use.

This prevents proxy, extension, or local-process issues from being mistaken for a browser download failure. Another device’s run record no longer blocks a local launch through a lease.

Before contacting support

Provide the browser version, last visible stage, complete error, approximate failure time, and steps already attempted. Redact account information and network credentials from screenshots. Never send passwords, proxy secrets, or other sensitive configuration.

Unstable connectivity, firewall or security-software interference, and insufficient disk space are also common Windows browser installation factors. See Google Chrome’s official installation troubleshooting guide.