Backup Job Fails with "Unable to cast object of type 'Newtonsoft.Json.Linq.JObject'" Error on vSAN 8.0.2 + Veeam v13

[rin]

Hello,
I am encountering a critical issue when running a backup job with Veeam Backup & Replication v13 (13.0.0.4967) in an environment using vSAN 8.0.2.
The backup job fails immediately, and the log shows the following error:
Error: Unable to cast object of type 'Newtonsoft.Json.Linq.JObject' to type 'System.Collections.Generic.Dictionary`2[System.String,System.Object]'. (System.InvalidCastException)
at Veeam.Backup.ViSoap.CVsanDataAmountsComputer...

Environment:

• Veeam Backup & Replication v13 (13.0.0.4967)

• vCenter/ESXi: 8.0.2

• vSAN: 8.0.2

• Backup proxy: HotAdd/Network mode both tested

• Repository: Linux Hardened Repository (also tested with Default Backup Repository, same result)

What I have tried:

• Changed repository (LHR and Default, both fail)

• Checked permissions and network connectivity (all OK)

• Confirmed that the error occurs before any data transfer

• No issues with authentication or storage space

Log excerpt:

[04.11.2025 14:59:22.045] <23> [000E] Error (1) Failed to fetch direct access data amount for proxy 'v13_Proxy_SA'
[04.11.2025 14:59:22.045] <23> [000E] Error (1) Unable to cast object of type 'Newtonsoft.Json.Linq.JObject' to type 'System.Collections.Generic.Dictionary`2[System.String,System.Object]'. (System.InvalidCastException)

Questions:

Is this a known issue with Veeam v13 and vSAN 8.0.2?
Are there any workarounds or patches available?
Has anyone else experienced this error?

Any advice or information would be greatly appreciated.
Thank you.

[david.domask]

Hi rin,

No known issues at first blush; please open a Support Case and let Veeam Support review the logs. As noted when creating a topic, all technical issues must go through Veeam Support, so please start with a case and share your case number once created.

Thanks!