From version 5.0 through 5.1.1, Breadcrumb NavXT included an extra plugin named “Breadcrumb NavXT 5.0 Migration Compatibility Layer”. The purpose of this plugin was to help overcome a bug in WordPress that causes plugin updates to break if the file containing the plugin header changes. Beginning in 5.2.0, Breadcrumb NavXT no longer includes the Breadcrumb NavXT 5.0 Migration Compatibility Layer.
If you still have the Breadcrumb NavXT 5.0 Migration Compatibility layer activated when upgrading to Breadcrumb NavXT 5.2.0 you may see the following PHP warning:
Warning: fopen(…/wp-content/plugins/breadcrumb-navxt/breadcrumb_navxt_admin.php): failed to open stream: No such file or directory in …/httpdocs/wp-includes/functions.php on line 4183
Warning: fread() expects parameter 1 to be resource, boolean given in …/httpdocs/wp-includes/functions.php on line 4186 Warning: fclose() expects parameter 1 to be resource, boolean in …/httpdocs/wp-includes/functions.php on line 4189
As long as Breadcrumb NavXT is activated, the warning message above can be ignored. It is only warning that the Breadcrumb NavXT 5.0 Migration Compatibility Layer was activated but is no longer available. If Breadcrumb NavXT is activated, then the Breadcrumb NavXT 5.0 Migration Compatibility Layer was not doing anything useful.
Migration Compatibility Layer Removal
Updating to Breadcrumb NavXT 5.2 should automatically remove the Breadcrumb NavXT 5.0 Migration Compatibility Layer. However, if you are on an earlier version, you may remove the Breadcrumb NavXT 5.0 Migration Compatibility Layer by performing the following, using a FTP client (or SSH/SCP client) navigate to your WordPress install’s plugins directory. Find the breadcrumb-navxt directory. Within the breadcrumb-navxt directory, there should be a file named breadcrumb_navxt_admin.php, delete this file.
-John Havlik
[end of transmission, stay tuned]