Open the guest VM and navigate to the services:

Start > run > services.msc

1. Check that the COM+ System Application service is listed as Started and that the startup type is listed as Manual.
2. Check that the COM+ Event System service is listed as Started and that the startup type is listed as Automatic.
3. Check that the Volume Shadow Copy service is not running and the startup type is listed as Manual.
4. The Microsoft Software Shadow Copy Provider service may or may not be started. Ensure that the startup type is listed as Manual.
5. Check that the VMware Snapshot Provider is not running and that the startup type is listed as Manual.

If you are having difficulty starting these services, consult Microsoft support before proceed to the following step.

Start > run > vssadmin list writers (run as an administrator user)

The output should list all the VSS writers in the virtual machine and each entry should look as follows:

 Make sure that the “State” is “Stable” and the “Last error” is “No error”. If you see any other results, you need to troubleshoot this specific VSS writer. (Please contact Microsoft support for additional troubleshooting steps). If you are sure that this specific VSS writer is not needed, you can simply disable it from running during the quiesced snapshot: see VMware Knowledge Base: Disabling specific VSS writers with VMware Tools.

Start > run > vssadmin list providers (run as an administrator user)

The output should be similar to this: 

 If you have a third-party provider, it may interfere with the quiescing operation. Try uninstalling any third-party VSS providers.

Start > run > eventvwr.msc > Windows log > Application

If you see the error, check the Event ID in the internet or contact Microsoft support for additional troubleshooting steps.

To start native Windows backup, you can use the following tools:

1. NTBackup utility for Windows 2003 
2. Wbamin utility for Windows Server 2008/2008 R2,  and above  
3. Windows Server Backup in Windows Server 2012 and above

Check the errors during the backup and the Windows Event Application logs for VSS errors. If you face any problems on this stage, please consult Microsoft support for additional troubleshooting steps.

In some cases, reinstallation or upgrading VMware tools helps to resolve the issue, see the link for additional information 

If the VM does not run a database (SQL, Exchange) you can disable VSS component of the VMware Tools and solve the problem:

Acronis Backup 12/12.5, Acronis Backup Cloud: disable Volume Shadow Copy Service for virtual machines in Backup Options (see product documentation)

Acronis Backup 11.7/Acronis Backup for VMware 9:

1.  Select the virtual machine in question on ESX server and go to Inventory -> Virtual Machine -> Install/Upgrade VMware Tools
2. This will launch the installation of VMware Tools on the virtual machine
3. Choose Modify
4. Uncheck the Volume Shadow Copy Services Support
5. Complete the modification
6. Reboot the virtual machine 

• Take a screenshot with the vSphere snapshot options (open the vSphere connection to the ESX host -> right-click on the machine -> take snapshot, make screenshot of the options selected).
• Take a screenshot of the vSphere snapshot result (result is displayed in the Recent Tasks at the bottom of the vSphere Client)

Open vSphere client > File > Export > Export System Logs

Obtaining Diagnostic Information for ESXi 5.x and 6.0 hosts using the vSphere Client

• Open the vSphere Client and connect to vCenter Server or directly to an ESXi 5.x host.
• Log in using an account with administrative privileges or with the Global.Diagnostics permission.
• Select an ESXi host, cluster, or datacenter in the inventory.
• Click the File > Export > Export System Logs.
• If a group of ESXi hosts are available in the selected context, select the host or group of hosts from the Source list.
• Click Next.
• In the System Logs pane, click Select All to collect diagnostic information for all the components. (Confirm that HungVM is not selected as this may cause a virtual machine failure.) 
• Click Next.

In the Download Location pane, click Browse and select a location on the client's disk where you have to save the support bundle.
Click Next.
In the Ready to Complete pane, review the summary and click Finish. The Downloading System Logs Bundles dialog appears and provides progress status for the creation and downloading of the support bundle from each source. A Generate system logs bundles task is created.

Obtaining Diagnostic Information for ESXi 5.x and 6.x hosts using the vSphere Web Client

• Open the vSphere Web Client.
• Log in using an account with administrative privileges or with the Global.Diagnostics permission.
• Select Hosts and Clusters from the Home tab.
• Select an ESXi host, or vCenter in the inventory.
• Click Actions. Select All vCenter Actions > Export System Logs...
• If a group of ESXi hosts are available in the selected context, select the host or group of hosts from the Source list. Click Next.
• In the System Logs pane, click Select All to collect diagnostic information about all components.
• Click Generate Log Bundle then click Download Log Bundle.

Obtaining Diagnostic Information for ESX/ESXi 4.x hosts using the vSphere Client

• Open the vSphere Client and connect to vCenter Server or directly to an ESXi 4.x host.
• Log in with an administrative user or other account with the Global.Diagnostics permission.
• Click the File menu, and select Export, Export System Logs.
• In the Export System Logs dialog, select the host or group of hosts to collect diagnostic information from.
• Specify a location on the client's disk to save the support bundle. Click the Browse button and select a directory. Click OK.
• A Generate system logs task is created. When complete, the logs will be downloaded by the client. 

Acronis system report from the Agent that is used for backing up the virtual machine:

• for Acronis Backup 12/12.5: see this article for instructions
• for Acronis Backup 11.5/11.7: see this article for instructions
• for Acronis Backup Cloud: see this article for instructions

Acronis Backup for VMware 9: Collect the logs via View -> Show Logs -> switch to dynamic  Logs tab ->  Save All To File

See: AcronisInfo Utility

Run diagnostic with VSS Doctor tool and click Save log to save diagnostic results as a plain-text report.

If saving VSS Doctor report is no possible for some reason, collect outputs of the vssadmin list writers command from the guest OS to check that there are no failing VSS writers.