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Update Mautic from 2.15.1 to 2.15.3

Your software
My Mautic version is:
My PHP version is: PHP: 7.1.33

Your problem
My problem is: The Mautic update could not complete successfully because of the following error: Could not open the ZIP archive to complete the update.

These errors are showing in the log:
Current Error Log
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 743: parser error : Opening and ending tag mismatch: div line 362 and article - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 746: parser error : Opening and ending tag mismatch: section line 358 and div - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 748: parser error : Opening and ending tag mismatch: div line 355 and section - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 849: parser error : StartTag: invalid element name - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 870: parser error : StartTag: invalid element name - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 902: parser error : Entity 'copy' not defined - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Copyright © 2019 Acquia, Inc. All Rights Reserved. Drupal is a - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 921: parser error : Opening and ending tag mismatch: body line 57 and div - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Specification mandates value for attribute defer - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : attributes construct error - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Couldn’t find end of Start Tag script line 924 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Opening and ending tag mismatch: html line 2 and script - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 925: parser error : Extra content at the end of the document - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <script src="/sites/acquia.com/files/js/js_Ko5Nk9HdCNkfdQ4ZiVUOR7gXNKCQMYiP0XgkE - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-29 12:03:35] mautic.WARNING: String could not be parsed as XML
[2019-12-29 12:06:10] mautic.WARNING: PHP Warning - file_put_contents(C:\xampp\htdocs\mautic0.ml\app\cache\prod/index.php?option=com_mauticdownload&task=downloadPackage&id=80): failed to open stream: No error - in file C:\xampp\htdocs\mautic0.ml\app\bundles\CoreBundle\Helper\UpdateHelper.php - at line 75
Steps I have tried to fix the problem:

You’re missing the PHP Zip extension.

https://stackoverflow.com/a/52954279

Thanks for the reply but, I followed the instructions but still get the same error.
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 746: parser error : Opening and ending tag mismatch: section line 358 and div - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 748: parser error : Opening and ending tag mismatch: div line 355 and section - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 849: parser error : StartTag: invalid element name - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 870: parser error : StartTag: invalid element name - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 902: parser error : Entity 'copy' not defined - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Copyright © 2019 Acquia, Inc. All Rights Reserved. Drupal is a - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 921: parser error : Opening and ending tag mismatch: body line 57 and div - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27 [] [] [2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Specification mandates value for attribute defer - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : attributes construct error - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Couldn’t find end of Start Tag script line 924 - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 924: parser error : Opening and ending tag mismatch: html line 2 and script - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): Entity: line 925: parser error : Extra content at the end of the document - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): <script src="/sites/acquia.com/files/js/js_Ko5Nk9HdCNkfdQ4ZiVUOR7gXNKCQMYiP0XgkE - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: PHP Warning - SimpleXMLElement::__construct(): ^ - in file C:\xampp\htdocs\mautic0.ml\vendor\debril\rss-atom-bundle\Debril\RssAtomBundle\Protocol\Parser\XmlParser.php - at line 27
[2019-12-30 20:53:46] mautic.WARNING: String could not be parsed as XML
[2019-12-30 20:54:07] mautic.WARNING: PHP Warning - file_put_contents(C:\xampp\htdocs\mautic0.ml\app\cache\prod/index.php?option=com_mauticdownload&task=downloadPackage&id=80): failed to open stream: No error - in file C:\xampp\htdocs\mautic0.ml\app\bundles\CoreBundle\Helper\UpdateHelper.php - at line 75
[2019-12-30 21:03:05] mautic.WARNING: PHP Warning - file_put_contents(C:\xampp\htdocs\mautic0.ml\app\cache\prod/index.php?option=com_mauticdownload&task=downloadPackage&id=80): failed to open stream: No error - in file C:\xampp\htdocs\mautic0.ml\app\bundles\CoreBundle\Helper\UpdateHelper.php - at line 75
[2019-12-30 21:06:45] mautic.WARNING: PHP Warning - file_put_contents(C:\xampp\htdocs\mautic0.ml\app\cache\prod/index.php?option=com_mauticdownload&task=downloadPackage&id=80): failed to open stream: No error - in file C:\xampp\htdocs\mautic0.ml\app\bundles\CoreBundle\Helper\UpdateHelper.php - at line 75
[2019-12-30 21:15:33] mautic.WARNING: PHP Warning - file_put_contents(C:\xampp\htdocs\mautic0.ml\app\cache\prod/index.php?option=com_mauticdownload&task=downloadPackage&id=80): failed to open stream: No error - in file C:\xampp\htdocs\mautic0.ml\app\bundles\CoreBundle\Helper\UpdateHelper.php - at line 75

Those are just warnings. Did you restart Apache?

Yes, many times…but still get the warnings

Please verify once again that ZIP is actually enabled
(e.g. by phpinfo, through <yourmautic>/s/sysinfo)

If so, you should probably switch to the console.
At least try downloading the lates upgrade.php to the Mautic directory first: https://raw.githubusercontent.com/mautic/mautic/master/upgrade.php
and run it from there:
php upgrade.php
then try again.

Still no luck? I’d now point you to Yosu’s great write-up: https://mauteam.org/mautic/mautic-admins/mautic-update-how-to-dont-click-that-button/

Good luck!
Ekke