Backup Client Release Notes (Windows)

Release Version 9.2.2.877

Improvements

• The Backup Client now shows a warning popup when less than 5 GB of space is available on the boot drive, helping ensure Backblaze can run reliably. This prevents silent failures due to insufficient disk space.
• The path C:\Users\...\AppData\Local\BraveSoftware\Brave-Browser\User Data\Default\Cache\Cache_Data was added to the exclusion list to prevent backing up temporary browser cache data from Brave.
• The Backup Client now excludes popular cloud storage providers from backup, including both mount points and cache directories. This prevents performance issues, excessive data usage, and unintended uploads from services like OneDrive, Google Drive, Dropbox, Box, iDrive, and others. This change aligns with Backblaze’s policy to back up only local and directly connected storage.
• A message was added to the Backup Client's Exclusions tab to clarify what data is not backed up. The message includes a “Learn More” link that directs users to the Supported Backup Data page for full details.
• Help page links were updated to avoid future dead URLs. References to help.backblaze.com were replaced with permanent URLs to ensure continued access to support content, especially for users on legacy Backup Client versions.
• The Inherit Backup State flow now shows a message when Email MFA is selected, as only SMS MFA is supported for this process. Email-based MFA is not currently compatible with Inherit Backup State.
• A security improvement was made to the Computer Backup Installer to prevent a potential privilege escalation issue. The Computer Backup Installer now verifies the code signature of the embedded MSI before execution, ensuring only trusted binaries are run.
• The Computer Backup Installer now supports mandatory email-based MFA during installation. This ensures users can complete authentication when MFA is required for their account.

Bug Fixes

• The bz_done file now maintains a consistent hguid during Inherit Backup State migration.
• A regression was resolved where the advanced installer did not correctly apply the -createaccount_or_signinaccount setting from the config file. The -cfg option was not recognized properly, and the setting was not written to bzinfo.xml.
• A local privilege escalation vulnerability affecting older versions of the Backup Client was resolved. The issue allowed a low-privilege user to abuse symbolic links and overwrite protected files using bztransmit64.exe. In current versions (9.2.2.859+), improved file handling and permissions prevent this attack vector.
• A vulnerability reported in older versions of the Backup Client that allowed arbitrary file deletion via symbolic link abuse has been resolved. This issue, which affected version 7.x, is no longer reproducible in version 9.2.2.859+ due to security improvements in file handling and directory permissions.
• BzClient now deletes old bz_done_internal_consistency.dat reports to prevent unbounded growth. This debug-only file previously grew indefinitely in some cases; the Backup Client now manages and removes older entries automatically.
• A crash in bztransmit related to Wi-Fi device listing was fixed by adding null checks in the WirelessAccessPointsQuery functions. This prevents unexpected failures when querying wireless network information on Windows systems. Fixed in version 9.2.2.869 and later.
• The Inherit Backup State flow now shows a message when Email MFA is selected, as only SMS MFA is supported for this process. Email-based MFA is not currently compatible with Inherit Backup State.
• A bug was resolved where the Backup Client failed to detect available updates, incorrectly showing "no new version" even when one existed. This was due to the version comparison being skipped in certain cases.
• A fix was implemented to address auto-update failures in older Backup Client versions (9.0.2.801–9.2.1.851), where updates would silently fail and show no new version available. The Backup Client now properly stops old processes before updating, preventing conflicts and ensuring successful upgrades. Fixed in 9.2.2.875 and 10.0.0.877+.

Release Version 9.2.1.859

Bug Fixes

• An issue was resolved where extremely large backup lists could take hours to load, potentially delaying backup operations. Performance has been improved for faster processing.
• Resolved an issue where certain internal backup metadata could be incorrectly modified during self-healing. This update ensures better consistency between what the Backup Client shows as backed up and what’s retained in storage.
• The Backup Client now limits this to a single log entry per several thousand lines to improve performance and reduce log size.

Release Version 9.2.1.851

Improvements

• Vulnerable dependencies in third-party libraries were upgraded.
• The authentication flow was updated to strictly follow the server API sequence, ensuring correct challenge handling and improved security.
• The Backup Client now detects bzdone lines containing multiple HGUIDs. It identifies affected FGUIDs, determines which files are still present on disk, and re-uploads them with a new, valid FGUID. For files that are no longer present, the Backup Client generates new x lines to mark them as expunged. This enhancement improves backup accuracy and ensures un-restorable files are correctly marked.
• After opening a Backblaze B2 session, the Computer Backup Installer now closes the session when it is no longer needed. This change improves overall session management and resource efficiency.

Bug Fixes

• A Safety Freeze alert was implemented for Backup Clients without a private encryption key (PEK) set, ensuring that users are notified of prolonged backup issues.
• An issue was resolved where duplicate installations created multiple backups.
• An issue was resolved where the auto-update process forced an unexpected system restart without warning.
• Logging was optimized to prevent excessive log file growth when attempting to back up unreadable cloud-based files. Behavior was adjusted to avoid backing up Backblaze B2 mounts for improved efficiency.
• Excessive and incorrect logging was resolved, reducing log file bloat and improving performance.
• An issue was resolved that caused a version servlet to reject valid data from the Backup Client.
• A mismatch was resolved in the cross-platform Backup Client related to version parsing. The Backup Client now handles version compatibility better to prevent these errors.
• Password generation was improved in the command-line installer to align with updated security best practices.
• A parameter handling issue was resolved that caused duplication and incorrect order in Computer Backup Installer commands.
• An issue was resolved that caused an “invalid login” error for users with weak account passwords.

Release Version 9.2.0.835

Improvements

• Restrictions were removed that prevented certain large files from being backed up.
• The threading mechanism was optimized to enhance performance and efficiency in data operations.
• Files with missing chunks are now automatically repaired when possible.

Bug Fixes

• Unnecessary files were removed to prevent the drive from reaching capacity.
• An issue was resolved that caused the Next button to briefly appear when the installer is re-run.
• An issue was resolved that caused an unresponsive Close button to appear on the "Install Complete" modal.
• An issue was resolved that caused the app to freeze and display an error when logging in with a single-sign on (SSO) account.
• An issue was resolved where selecting the wrong SSO caused the client to time out.

Release Version 9.1.0.833

Improvements

• The process to check for existing installations was improved to prevent corrupt installations.
• The Windows Backup Client installer was enhanced with performance and reliability optimizations for smoother installations and upgrade and downgrade experiences.
• Various security improvements were made to the Windows Backup Client installer.

Bug Fixes

• An issue was resolved that caused an unnecessary Windows User Account Control (UAC) modal to appear when auto-updates are enabled.
• An issue was resolved that caused errors when installing the Windows Backup Client for Groups.
• An issue was resolved that caused the Windows Backup Client installer to fail when used with Microsoft Office 365 Single Sign-On (SSO).
• An issue was resolved that caused an installation to fail on systems that do not use C: as a boot drive.
• An issue was resolved that caused an error to occur when a custom installer was already used or expired.
• An issue was resolved that caused the Backup Client to freeze and display an error during installation when logging in with an SSO account.
• An issue was resolved that prevented the Backup Client from installing when a gift code was used.

Release Version 9.1.0.817

Improvements

• Improvements were implemented to strengthen the Windows Installer, laying the groundwork for a future installation.
• cURL version 8.9.1 is now supported.
• The "Skipped Files" process was enhanced for better performance and more efficient file handling.
• The Backup Client was upgraded to support OpenSSL v3.3.2.

Bug Fix

• An issue was resolved that caused the Backup Client to crash when the number of top-level directories exceeded 200,000 entries.

Release Version 9.0.2.801

Bug Fix

• An issue was resolved where files were prematurely expunged before the license expired.

Release Version 9.0.2.789

Improvements

• Improvements were made that enhanced security.
• Improvements were made to error messages to provide more information during installation.

Bug Fixes

• A problem with the installer, where it would become unresponsive, was resolved.

Release Version 9.0.2.783

Improvements

• Notifications and the process for handling the end-of-life status of an installed Backup Client version were improved through various enhancements.

Bug Fixes

• The correct version history is now displayed in the Control Panel after a Backup Client upgrade.
• An upgrade link now appears so a user can upgrade to “Forever” version history.
• Version History text and stats persist after upgrading the Backup Client.
• Non-functional updates were made to the Computer Backup Installer.
• Help Center text and a link was added to the Backup Client Control Panel for Windows 11.

Release Version 9.0.1.777

Improvements

• A Show Password button is now displayed on the “Private Encryption Key” window. The warning message text was also updated.
• The process for handling the end-of-life status of an installed client version was improved through various enhancements.

Bug Fixes

• Files that contain a resource fork no longer fail when scheduled for backup.
• Version History settings are now retained after an “Inherit Backup State” is completed.
• Additional SHA-1 checks were implemented to prevent corrupted backup files before uploading to servers.
• If a large file existed that required making a full copy of that large file to back up and a user deletes that large file from their computer, a “Low on Disk Space” error is no longer returned.

Release Version 9.0.1.767

Improvements

• Restore logs dynamically update to be readable while a restore progresses.

Bug Fixes

• Log files are now removed periodically to prevent them from increasing indefinitely and filling up drive space.