I have a staging site setup and following the plugin upgrade to 1.9.5 I get a critical error on the front-end 

https://staging.islandnaturetrust.ca/

Notice: is_singular was called incorrectly. Conditional query tags do not work before the query is run. Before then, they always return false. Please see Debugging in WordPress for more information. (This message was added in version 3.1.0.) in /home/isla6524/staging.islandnaturetrust.ca/wp-includes/functions.php on line 5311

Fatal error: Uncaught Error: Call to a member function get_page_permastruct() on null in /home/isla6524/staging.islandnaturetrust.ca/wp-includes/link-template.php:378 Stack trace: #0 /home/isla6524/staging.islandnaturetrust.ca/wp-includes/link-template.php(340): _get_page_link(Object(WP_Post), false, false) #1 /home/isla6524/staging.islandnaturetrust.ca/wp-content/plugins/bp-profile-search/bps-directory.php(45): get_page_link(Object(WP_Post)) #2 /home/isla6524/staging.islandnaturetrust.ca/wp-content/plugins/bp-profile-search/bps-directory.php(22): bps_directories() #3 /home/isla6524/staging.islandnaturetrust.ca/wp-content/plugins/bp-profile-search/bps-directory.php(318): bps_is_directory() #4 /home/isla6524/staging.islandnaturetrust.ca/wp-includes/class-wp-hook.php(289): bps_custom_directory(Array) #5 /home/isla6524/staging.islandnaturetrust.ca/wp-includes/plugin.php(212): WP_Hook->apply_filters(Array, Array) #6 /home/isla6524/staging.islandnaturetrust.ca/wp-content/plugins/buddypress/bp-core/bp-core-functions.php(551): a in /home/isla6524/staging.islandnaturetrust.ca/wp-includes/link-template.php on line 378

Looks like a conflict with BP Profile Search plugin. Once disabled and with Wp Foro active - the website functions again.

Not sure how to fix this if someone can help?

Thanks in advance