This is a regression introduced by 0031017.

category_update() expects $p_status parameter to be int|null so I believe there is a missing type cast in manage_proj_cat_update.php line 78.

I do not have access to a PostgreSQL instance at the moment so I can't test and confirm for sure. Until I do you may want to try this as a workaround, and let me know how it goes:

diff --git a/manage_proj_cat_update.php b/manage_proj_cat_update.php
index 4d715c206..bf8224470 100644
--- a/manage_proj_cat_update.php
+++ b/manage_proj_cat_update.php
@@ -75,7 +75,7 @@ if( mb_strtolower( $f_name ) != mb_strtolower( $t_old_name ) ) {
        category_ensure_unique( $t_project_id, $f_name );
 }

-category_update( $f_category_id, $f_name, $f_assigned_to, $f_status );
+category_update( $f_category_id, $f_name, $f_assigned_to, (int)$f_status );

 form_security_purge( 'manage_proj_cat_update' );

Patch fixes the problem. Thank you.

@dregad what do you think about reverting your change but changing
$f_status = gpc_get_bool( 'status', CATEGORY_STATUS_DISABLED );
to
$f_status = gpc_get_int( 'status', CATEGORY_STATUS_DISABLED );