Index: src/wp-admin/includes/ajax-actions.php
===================================================================
--- src/wp-admin/includes/ajax-actions.php	(revision 38090)
+++ src/wp-admin/includes/ajax-actions.php	(working copy)
@@ -3788,13 +3788,18 @@
 function wp_ajax_search_plugins() {
 	check_ajax_referer( 'updates' );
 
-	global $wp_list_table, $hook_suffix, $s;
-	$hook_suffix = 'plugins.php';
+	$pagenow = wp_unslash( $_POST['pagenow'] );
+	if ( 'plugins-network' === $pagenow || 'plugins' === $pagenow ) {
+		set_current_screen( $pagenow );
+	}
 
 	/** @var WP_Plugins_List_Table $wp_list_table */
-	$wp_list_table = _get_list_table( 'WP_Plugins_List_Table' );
-	$status        = array();
+	$wp_list_table = _get_list_table( 'WP_Plugins_List_Table', array(
+		'screen' => get_current_screen(),
+	) );
 
+	$status = array();
+
 	if ( ! $wp_list_table->ajax_user_can() ) {
 		$status['errorMessage'] = __( 'Sorry, you are not allowed to manage plugins for this site.' );
 		wp_send_json_error( $status );
@@ -3806,6 +3811,7 @@
 		'action'      => null,
 	) ), network_admin_url( 'plugins.php', 'relative' ) );
 
+	global $s;
 	$s = sanitize_text_field( $_POST['s'] );
 
 	$wp_list_table->prepare_items();
@@ -3822,20 +3828,22 @@
  * Ajax handler for searching plugins to install.
  *
  * @since 4.6.0
- *
- * @global WP_List_Table $wp_list_table Current list table instance.
- * @global string        $hook_suffix   Current admin page.
  */
 function wp_ajax_search_install_plugins() {
 	check_ajax_referer( 'updates' );
 
-	global $wp_list_table, $hook_suffix;
-	$hook_suffix = 'plugin-install.php';
+	$pagenow = wp_unslash( $_POST['pagenow'] );
+	if ( 'plugin-install-network' === $pagenow || 'plugin-install' === $pagenow ) {
+		set_current_screen( $pagenow );
+	}
 
 	/** @var WP_Plugin_Install_List_Table $wp_list_table */
-	$wp_list_table = _get_list_table( 'WP_Plugin_Install_List_Table' );
-	$status        = array();
+	$wp_list_table = _get_list_table( 'WP_Plugin_Install_List_Table', array(
+		'screen' => get_current_screen(),
+	) );
 
+	$status = array();
+
 	if ( ! $wp_list_table->ajax_user_can() ) {
 		$status['errorMessage'] = __( 'Sorry, you are not allowed to manage plugins for this site.' );
 		wp_send_json_error( $status );
Index: src/wp-admin/js/updates.js
===================================================================
--- src/wp-admin/js/updates.js	(revision 38090)
+++ src/wp-admin/js/updates.js	(working copy)
@@ -2033,7 +2033,8 @@
 					_ajax_nonce: wp.updates.ajaxNonce,
 					s:           $( '<p />' ).html( $( this ).val() ).text(),
 					tab:         'search',
-					type:        $( '#typeselector' ).val()
+					type:        $( '#typeselector' ).val(),
+					pagenow:     pagenow
 				}, { type: 'term' } );
 
 			if ( wp.updates.searchTerm === data.s ) {
@@ -2043,7 +2044,7 @@
 			}
 
 			if ( history.pushState ) {
-				history.pushState( null, '', location.href.split( '?' )[ 0 ] + '?' + $.param( _.omit( data, '_ajax_nonce' ) ) );
+				history.pushState( null, '', location.href.split( '?' )[ 0 ] + '?' + $.param( _.omit( data, [ '_ajax_nonce', 'pagenow' ] ) ) );
 			}
 
 			if ( 'undefined' !== typeof wp.updates.searchRequest ) {
@@ -2071,7 +2072,8 @@
 		$pluginSearch.on( 'keyup input', _.debounce( function( event ) {
 			var data = {
 				_ajax_nonce: wp.updates.ajaxNonce,
-				s:           event.target.value
+				s:           event.target.value,
+				pagenow:     pagenow
 			};
 
 			// Clear on escape.