One server has issue to sync data with Azure storage

Question

One server has issue to sync data with Azure storage

Yuan Wenrong 0

We have a server can't sync data with Azure storage suddently. Network connectively test is failed on server side, but port 443 test is succssful

kagiyama yutaka 5,410 Reputation points

2026-09-09T02:58:07.6333333+00:00

Could you add the server OS version, the File Sync agent version, and the exact output of

Test‑StorageSyncNetworkConnectivity? Without those, it's hard to tell which layer of the File Sync pipeline is failing.

2 answers

Your answer

kagiyama yutaka 5,410 Reputation points

2026-09-09T02:58:07.6333333+00:00

Could you add the server OS version, the File Sync agent version, and the exact output of

Test‑StorageSyncNetworkConnectivity? Without those, it's hard to tell which layer of the File Sync pipeline is failing.

Answer 1

kagiyama yutaka 5,410

I think the sync stops because the server can’t reach one of the Azure File Sync service URLs, and like I said just run Test‑StorageSyncNetworkConnectivity and open the first failed URL right on the server. If that host’s blocked, just let it through the firewall and proxy and the agent starts talking again.

0 comments

Answer 2

If port 443 succeeds but the Azure File Sync network connectivity test fails, the server can reach HTTPS generally, but it likely cannot reach the required Azure File Sync service endpoints or is blocked by proxy, firewall, or TLS cipher suite configuration.

Use this troubleshooting path on the affected server:

Check the Azure File Sync agent event log
- Open Event Viewer.
- Go to Applications and Services\Microsoft\FileSync\Agent.
- Look for event ID 9301 in the Telemetry event log.
- If the log shows "GetNextJob completed with status: -2134347756", the server cannot communicate with the Azure File Sync service because of firewall, proxy, or TLS cipher suite order configuration.
Test Azure File Sync endpoint connectivity
- Run Test-StorageSyncNetworkConnectivity on the server.
- This checks connectivity to the required service endpoints, which is more specific than a basic port 443 test.
Verify firewall rules
- Confirm outbound port 443 is allowed.
- If the firewall restricts traffic by destination, make sure the Azure File Sync domains listed in the firewall documentation are allowed.
- Also verify FileSyncSvc.exe is not blocked by the firewall.

Verify proxy configuration

If the server uses a proxy, confirm the Azure File Sync proxy settings are configured correctly.
Run:

   $agentPath = "C:\Program Files\Azure\StorageSyncAgent"
   Import-Module "$agentPath\StorageSync.Management.ServerCmdlets.dll"
   Get-StorageSyncProxyConfiguration

Check TLS cipher suite configuration
- If TLS cipher suite order is managed on the server, ensure these TLS 1.2 cipher suites are available for Azure File Sync:
  - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
  - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
  - TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
  - TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
- Cipher suite order can be adjusted by Group Policy or TLS PowerShell cmdlets.
If sync does not resume immediately after fixing connectivity
- Azure File Sync may wait up to 30 minutes before starting another sync session if no changes are detected.
- To force a sync session, restart the Storage Sync Agent (FileSyncSvc) service or make a change to a file or directory in the server endpoint path.

If the server appears offline in the portal and event 9301 shows communication failures, focus first on firewall/proxy/TLS rather than basic port testing.

References: