Just tried to upgrade SEO Backpack (which there is no category for??!!) and I got SyntaxError: Unexpected token < in JSON at position 0

Then the upgrade just stopped and did not rollback.

The error is longer than that, but I see no way to upload a picture.

Then I went into SEO Backpack module and tried to test a Crawler page and got this error: 

Fatal error: Uncaught Error: Class 'HtmlDom' not found in /home/bdatest4/public_html/agstore/admin/controller/module/isenselabs_seo.php:1240 Stack trace: #0 /home/bdatest4/public_html/agstore/vqmod/vqcache/vq2-system_modification_system_engine_action.php(65): ControllerModuleiSenseLabsSeo->get_crawler_data(Array) #1 /home/bdatest4/public_html/agstore/system/engine/front.php(34): Action->execute(Object(Registry)) #2 /home/bdatest4/public_html/agstore/system/engine/front.php(29): Front->execute(Object(Action)) #3 /home/bdatest4/public_html/agstore/admin/index.php(175): Front->dispatch(Object(Action), Object(Action)) #4 {main} thrown in /home/bdatest4/public_html/agstore/admin/controller/module/isenselabs_seo.php on line 1240

Although the install did not finish, I do see the version number has changed to 2.5

Thanks in advance for any help....