Symptoms

Accessing Tools & Settings > Backup Manager results in error:

Failed to parse response. Reason: XML error at line 1 column 1. Error message: Not well-formed (invalid token) Process output: Cannot create process: C:\PROGRA~2\PARALL~1\Plesk\Additional\Python\python.exe "C:\Program Files (x86)\Parallels\Plesk\admin\bin\PMMcli-runner.py"  --get-dumps-list
---------------------- Debug Info -------------------------------
0: PMMConnector.php:641
        PMMConnector->getResponse(object of type StreamXMLReader)
1: PMMConnector.php:70
        PMMConnector->getDumpList(object of type PMMDumpsStorageCredentials, object of type PMMObjectSpecification)
2: BackupLocalRepositoryList.php:18
        BackupLocalRepositoryList->fetchBackupLocalRepositoryList()
3: cList.php:87
        cList->fetchList()
4: cList.php:109
        cList->init()
5: backup.abstract-repository.php:68
        __backup__abstract_repository->accessItemsList(string 'GET', NULL null)
6: backup.abstract-repository.php:27
        __backup__abstract_repository->accessItem(string 'GET', NULL null)
7: UIPointer.php:619
        UIPointer->access(string 'GET')
8: plesk.php:36

or:

    Internal error: Failed to parse response. Reason: Failed to read data from stream Process output:
    Message Failed to parse response. Reason: Failed to read data from stream Process output:
    File    PMMConnector.php
    Line    708
    Type    PleskPMMResponseException

or:

    Internal error: Failed to parse response. Reason: Failed to read data from stream Process output:
    Message Failed to parse response. Reason: Failed to read data from stream Process output:
    File    PMMConnector.php
    Line    839
    Type    PleskPMMResponseException

In %plesk_dir%\admin\logs\php_error.log there is a following message:

    PleskPMMResponseException: Failed to parse response. Reason: Failed to read data from stream         Process output: 
    file: %plesk_dir%\admin\plib\backup\protocol\PMMConnector.php
    line: 708
    code: 0
    trace: #0 %plesk_dir%\admin\plib\backup\protocol\PMMConnector.php(299):         PMMConnector->getResponse(Object(StreamXMLReader))

or:

    [2017-06-06 09:24:01] DEBUG [util_exec] [5936589127c4b] Starting: pmmcli --get-tasks-list, stdin: 
[2017-06-06 09:24:01] DEBUG [util_exec] [5936589127c4b] Finished in 0.0224s, Error code: TRUE, stdout: , stderr: 
[2017-06-06 09:24:01] ERR [1] PleskPMMResponseException: Failed to parse response. Reason: Failed to read data from stream Process output: 
file: C:\Parallels\Plesk\admin\plib\backup\protocol\PMMConnector.php
line: 839
code: 0
trace: #0 C:\Parallels\Plesk\admin\plib\backup\protocol\PMMConnector.php(411): PMMConnector->getResponse(object of type StreamXMLReader)
#1 C:\Parallels\Plesk\admin\plib\CommonPanel\Controller\Action\Backup\Trait.php(1638): PMMConnector->getTasksList(array, array, integer '1', string 'server')
#2 C:\Parallels\Plesk\admin\plib\CommonPanel\Controller\Action\Backup\Trait.php(1337): Admin_BackupController->_getStatuses()
#3 C:\Parallels\Plesk\admin\plib\CommonPanel\Controller\Action\Backup\Trait.php(32): Admin_BackupController->_getBackupList()
#4 C:\Parallels\Plesk\admin\externals\Zend\Controller\Action.php(516): Admin_BackupController->listAction()
#5 C:\Parallels\Plesk\admin\externals\Zend\Controller\Dispatcher\Standard.php(308): Zend_Controller_Action->dispatch(string 'listAction')
#6 C:\Parallels\Plesk\admin\externals\Zend\Controller\Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(object of type Zend_Controller_Request_Http, object of type Zend_Controller_Response_Http)
#7 C:\Parallels\Plesk\admin\plib\Application\Web.php(39): Zend_Controller_Front->dispatch(NULL null)
#8 C:\Parallels\Plesk\admin\htdocs\application.php(15): Plesk\Application_Web->run()

Running PMMcli.exe binary in command line outputs an error:

    "%plesk_bin%\PMMcli.exe" --help 
    C:\Program Files (x86)\Parallels\Plesk\admin\bin>PMMcli.exe --help
    Traceback (most recent call last):
    File "C:\\Program Files (x86)\Parallels\Plesk\admin\bin\PMMcli-runner.py", line 14, in <module> 
    import pmmcli
    File "C:\\Program Files (x86)\Parallels\Plesk\admin\share\pmmcli\pmmcli.py", line 8, in <module> 
    import libxml2
    ImportError: Bad magic number in C:\Program Files (x86)\Parallels\Plesk\admin\lib\python\libxml2\libxml2.pyc

or

C:\Users\Administrator>"%plesk_bin%\PMMcli.exe" --help
Traceback (most recent call last):
  File "C:\Parallels\Plesk\admin\bin\PMMcli-runner.py", line 13, in 
    import pmmcli
  File "C:\Parallels\Plesk\admin\share\pmmcli\pmmcli.py", line 13, in 
    from xml.parsers.expat import ExpatError
ImportError: cannot import name ExpatError

Cause

Corrupted Python installation.

Resolution

Reinstall Python using the following steps:

1. Launch 'python.msi' intsaller from C:\ParallelsInstaller\parallels\PANEL-WIN_<plesk_version>\thirdparty-msi-Windows-any-x86_64 folder for the version of Plesk 12.0 and lower, and launch 'plesk-python.msi' C:\ParallelsInstaller\parallels\PANEL-WIN_<plesk_version>\dist-msi-Microsoft-2003-i386 for the version 12.5 and higher. If file 'python.msi' or 'plesk-python.msi' is absent, download it from the following site: http://autoinstall-win.plesk.com .

   Note: For Plesk 12.5 upgraded from previous version, python.msi should be taken from C:\ParallelsInstaller\parallels\PANEL-WIN_12.0.18\ hirdparty-msi-Windows-any-x86_64

2. Follow the installation wizard instructions, specify C:\Program Files (x86)\Parallels\Plesk\Additional\Python\ as installation path if required.

3. If the issue persists for the version 12.0 and lower, launch 'plesk-python.msi' from C:\ParallelsInstaller\parallels\PANEL-WIN_<plesk_version>\dist-msi-Microsoft-2003-i386 folder & reinstall Plesk Python.