This bulletin covers Acronis Cyber Protect Cloud 26.09 and the August 26.08 release, including the two hotfixes that have shipped since. Every item carries the build or date Acronis published it under.

Check which build you are actually on

26.08 has moved twice since it first shipped, so “we are on 26.08” no longer tells you much:

• 26.8.42957 — 26.08 general availability, August 2026
• 26.8.43043 — 26.08 Hotfix 1, August 2026
• 26.8.43120 — 26.08 Hotfix 2, September 2026. This is the build the 26.08 release notes now list for Windows, Mac and Linux.
• 26.9.43144 — Cyber Protect Cloud 26.09, September 2026

If your agents are still reporting 26.8.42957, you are two hotfixes behind on a release you may believe is current.

Plan for this now: macOS 12 support ends

Acronis states it plainly in the 26.08 notes: “Starting with the 26.09 release, the Cyber Protection agent for Mac will no longer support macOS 12 and earlier versions.” If you protect Macs on Monterey or older, that is an upgrade project, not a checkbox, and it is already in effect.

Worth acting on from 26.09

You run Agent for Hyper-V. The agent could be removed during an update when WMI was unresponsive, after which the host’s virtual machines disappeared from the console (ABR-433933). Losing protection silently during a routine update is the most serious item in this release.

You back up Microsoft 365. Two fixes: mailbox backups failing with an unknown error when the mailbox was not enabled for the REST API (ABR-442908), and a “Failed to register a backup in backup file” warning (ABR-441969).

You use Data Loss Prevention with IPv6. DLP did not block generative AI services over IPv6 (DEVLOCK-7265), and the host allowlist was not applied to IPv6 hosts, which broke functions such as vulnerability assessment (DEVLOCK-6594). If you rely on DLP to control AI tool usage and your network is dual-stack, this was a real gap.

Also fixed in 26.09: intermittent failures of scheduled VMware virtual machine backups reporting that an ESXi host was not selected or not found in vCenter (ABR-361367); full-machine recovery from Impossible Cloud storage failing (ABR-426877); a managed machine service crash (ABR-439411); agent update and uninstall failing because the ngscan filter driver did not unload within the timeout (KERNEL-21240); Microsoft 365 service connections for Acronis XDR reverting to “Not configured” (AMP-52032); disaster recovery status shown incorrectly as “Not enabled” (DRAAS-26203); scheduled reports not generated or sent because the scheduler service restarted frequently (ADP-51631); and a false “Unable to connect to the URL filtering web browser extension” alert during Chrome background downloads (AMP-56376).

Worth acting on from 26.08

You run Linux workloads. On machines using multiqueue block devices, the operating system could crash with a kernel NULL pointer dereference during a backup (ABR-434800). A second, separate multiqueue crash — this one during snapshot driver unloading — was fixed later in 26.08 Hotfix 2, which is another reason to be on 26.8.43120 rather than the original build.

You have Data Loss Prevention enabled. The DLP module could cause access to SMB network shares to stall or fail, with Windows Explorer freezing or crashing (DEVLOCK-7164).

You deploy to Windows ARM64 devices. Agent installation failed intermittently with error 1603 (ABR-435922).

Also fixed in 26.08: an incorrect “Backup failed” status in the console when the most recent backup had actually succeeded (PLTFRM-93001); protection plans showing “Succeeded with warnings” when no errors or alerts existed (PLTFRM-91965); browsing and indexing failures on Microsoft 365 mailbox backups containing email items without a parent folder (ABR-414476); credential errors when several protection plans used the same SMB share (ABR-429059); file recovery failures to GPT-disk machines with an incorrect protective MBR (ABR-329053); file-level backups using policy rules failing when the parent directory held more than 5,000 items (ABR-314208); new folders under a partner tenant not inheriting enabled applications, which made moving tenants into the folder fail (PLTFRM-69757); customised report names being replaced with defaults (ADP-55564); and web-based remote desktop connections being repeatedly interrupted after failed authentication attempts (ADP-32882).

Two things that catch people out

Neither of these is new, but both surprise teams often enough to be worth repeating.

Manual cloud-to-cloud backups are rate limited. You get 10 manual runs per Microsoft 365 or Google Workspace organisation per hour. Once you hit the cap the allowance resets to one run in the following hour and then grows by one each hour until it is back to 10. If your team runs ad-hoc backups during a migration or an investigation, plan around it.

Public cloud access certificates expire annually. Acronis assigns a free certificate automatically and it is valid for one year. Renew it from Infrastructure > Public clouds, select the connection, then Renew access.

Security updates

Both releases carry security fixes, published as separate Acronis advisories rather than in the release notes: UPD-2608-e38e-7865 for 26.08 and UPD-2609-169a-de33 for 26.09. Read them against your own exposure before scheduling the rollout.

Need help planning the update?

Arrosoft manages Acronis environments for partners and their customers across APAC and North America. If you would like us to check which agent builds your estate is actually running and schedule the rollout, get in touch.

Full detail: Cyber Protect Cloud 26.08 release notes and the Cyber Protection agent release history.