Some mandatory parameters are missing ("webform") to generate a URL for route

Also experiencing this error.

find that from webform.module from line 258 but dont know why it does not work

// ISSUE:
// Devel routes do not use 'webform' parameter which throws the below error.
// Some mandatory parameters are missing ("webform") to generate a URL for
// route "entity.webform_submission.canonical"
//
// WORKAROUND:
// Make sure webform parameter is set for all routes.
if (strpos($route_name, 'entity.webform_submission.devel_') === 0 || $route_name === 'entity.webform_submission.token_devel') {
foreach ($data['tabs'] as $tab_level) {
foreach ($tab_level as $tab) {
/** @var \Drupal\Core\Url $url */
$url = $tab['#link']['url'];
$tab_route_name = $url->getRouteName();
$tab_route_parameters = $url->getRouteParameters();

if (strpos($tab_route_name, 'entity.webform_submission.devel_') !== 0) {
$webform_submission = WebformSubmission::load($tab_route_parameters['webform_submission']);
$url->setRouteParameter('webform', $webform_submission->getWebform()->id());
}
}
}
}

upgrade to webform 6.2.7 it does not work also

if a form has no submission, it works fine.
after submitted one test submission, it does not work.

I got the same problem and was in need to report results so I had to pull the results from the database. A view to report seems also possible.

SELECT subm.serial, subm.remote_addr, subm.sid, submdata.name, submdata.property, submdata.delta, submdata.value 
FROM webform_submission as subm 
INNER JOIN webform_submission_data as submdata 
ON submdata.sid=subm.sid 
WHERE subm.webform_id='<<webform_id>>’;