63983: Acronis True Image 2020: Backup to Cloud fails with "The certification server is unavailable" or "The server reply contains an XML file of invalid format"

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Last update: 14-05-2021


Backup to Cloud storage fails with the following error:

The certification server is unavailable. Check your Internet connection or try again later


The server reply contains an XML file of invalid format


DNS resolver cannot resolve Acronis Cloud Storage server name.


1. Make sure that Acronis services are not blocked by firewall and all required ports are open: see Firewall settings for Acronis products

2. Verify connection to Acronis servers using Acronis Cloud Connection Verification Tool. If there are any issues with connection, the tool will provide recommendations on how to proceed

3. Temporarily disable antivirus and check if backup succeeds. If backup works when antivirus is disabled, check if your antivirus uses custom DNS settings.

4. Check the contents of the file C:\Windows\System32\drivers\etc\hosts. If there are any lines containing "acronis", delete these lines and save the file.

Collect information

If the above instructions did not help, collect the following information and contact Acronis Support:

  1. Output of Acronis Cloud Connection Verification Tool: report AcronisCloudReport_<computername>.txt is saved in the same folder where the tool is saved; or take screenshots of the output.
  2. Acronis True Image System Report: see instructions here