Site stuck in maintenance mode after migration to D8


I migrated a D7 site to D8 as instructed. The content has come over but I can’t get the site out of maintenance mode because I have 2 “This block is broken or missing. You may be missing content or you might need to enable the original module.”
I have tried a couple of suggestions to fix this by adding Recreate Block Content and Fixed Block Content modules but the errors persist.

During the site migration, these modules could not be converted to D8. Is this the problem? I am fairly new to Drupal.

acl 
aggregator  
backup_migrate  
basic_cart  
calendar    
captcha 
chain_menu_access   
chr 
civicrm 
civicrmtheme    
ckeditor    
forum   
forum_access    
googleanalytics 
image_captcha   
imce    
libraries   
mailsystem  
messaging   
messaging_htmlmail  
messaging_mail  
messaging_template  
notifications   
notifications_content   
notifications_forum 
notifications_tags  
oauth_common    
payment 
paypal_payment  
paypal_payment_ipn  
robotstxt   
site_verify 
twitter 
twitter_actions 
twitter_post    
views   
views_rss   
webform 
webform_paypal  
xmlsitemap  
xmlsitemap_custom   
xmlsitemap_engines  
xmlsitemap_menu 
xmlsitemap_node 
xmlsitemap_taxonomy 
xmlsitemap_user