/var/www/wiki/mediawiki/core/includes/specials/SpecialImport.php:244:
object(MWException)[999]
  protected 'message' => string 'XML error at line 1: Validation failed: no DTD found !' (length=54)
  private string 'string' (Exception) => string '' (length=0)
  protected 'code' => int 0
  protected string 'file' => string '/var/www/wiki/mediawiki/core/includes/import/WikiImporter.php' (length=61)
  protected int 'line' => int 1372
  private array 'trace' (Exception) => 
    array (size=10)
      0 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/import/WikiImporter.php' (length=61)
          'line' => int 694
          'function' => string 'syntaxCheckXML' (length=14)
          'class' => string 'WikiImporter' (length=12)
          'type' => string '->' (length=2)
      1 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/specials/SpecialImport.php' (length=64)
          'line' => int 239
          'function' => string 'doImport' (length=8)
          'class' => string 'WikiImporter' (length=12)
          'type' => string '->' (length=2)
      2 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/specials/SpecialImport.php' (length=64)
          'line' => int 112
          'function' => string 'doImport' (length=8)
          'class' => string 'SpecialImport' (length=13)
          'type' => string '->' (length=2)
      3 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/specialpage/SpecialPage.php' (length=65)
          'line' => int 700
          'function' => string 'execute' (length=7)
          'class' => string 'SpecialImport' (length=13)
          'type' => string '->' (length=2)
      4 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/specialpage/SpecialPageFactory.php' (length=72)
          'line' => int 1463
          'function' => string 'run' (length=3)
          'class' => string 'SpecialPage' (length=11)
          'type' => string '->' (length=2)
      5 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/MediaWiki.php' (length=51)
          'line' => int 324
          'function' => string 'executePath' (length=11)
          'class' => string 'MediaWiki\SpecialPage\SpecialPageFactory' (length=40)
          'type' => string '->' (length=2)
      6 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/MediaWiki.php' (length=51)
          'line' => int 917
          'function' => string 'performRequest' (length=14)
          'class' => string 'MediaWiki' (length=9)
          'type' => string '->' (length=2)
      7 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/includes/MediaWiki.php' (length=51)
          'line' => int 573
          'function' => string 'main' (length=4)
          'class' => string 'MediaWiki' (length=9)
          'type' => string '->' (length=2)
      8 => 
        array (size=5)
          'file' => string '/var/www/wiki/mediawiki/core/index.php' (length=38)
          'line' => int 50
          'function' => string 'run' (length=3)
          'class' => string 'MediaWiki' (length=9)
          'type' => string '->' (length=2)
      9 => 
        array (size=3)
          'file' => string '/var/www/wiki/mediawiki/core/index.php' (length=38)
          'line' => int 46
          'function' => string 'wfIndexMain' (length=11)
  private ?Throwable 'previous' (Exception) => null
  public 'xdebug_message' => string '<tr><th align='left' bgcolor='#f57900' colspan="5"><span style='background-color: #cc0000; color: #fce94f; font-size: x-large;'>( ! )</span> MWException: XML error at line 1: Validation failed: no DTD found ! in /var/www/wiki/mediawiki/core/includes/import/WikiImporter.php on line <i>1372</i></th></tr>
<tr><th align='left' bgcolor='#e9b96e' colspan='5'>Call Stack</th></tr>
<tr><th align='center' bgcolor='#eeeeec'>#</th><th align='left' bgcolor='#eeeeec'>Time</th><th align='left' bgcolor='#eeeeec'>Memory</th'... (length=12300)

reedy@ubuntu64-web-esxi:~$ php8.1 -a
Interactive shell

php > echo LIBXML_DOTTED_VERSION;
2.9.14
php > ^Dreedy@ubuntu64-web-esxi:~$ php8.2 -a
Interactive shell

php > echo LIBXML_DOTTED_VERSION;
2.9.14
php > ^Dreedy@ubuntu64-web-esxi:~$ php8.0 -a
Interactive mode enabled

php > echo LIBXML_DOTTED_VERSION;
2.9.14

php > echo LIBXML_DOTTED_VERSION;
2.9.14
php >

ii  libxml2:amd64                         2.9.14+dfsg-0.1+ubuntu22.04.1+deb.sury.org+1                         amd64        GNOME XML library