This thread is resolved. Here is a description of the problem and solution.
Problem:
The module manager admin page has a fatal PHP error:
PHP Fatal error: Uncaught Error: Cannot use object of type stdClass as array in /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/types/vendor/toolset/types/embedded/includes/module-manager.php:308
Solution:
This issue is already fixed following an update to Types.
This support ticket is created 6 years, 5 months ago. There's a good chance that you are reading advice that it now obsolete.
This is the technical support forum for Toolset - a suite of plugins for developing WordPress sites without writing PHP.
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I could see the issue on your site and took a copy to test locally, where I saw in the logs that a fatal error was appearing on the module manager page, i.e.
[05-Jul-2018 09:13:08 UTC] PHP Fatal error: Uncaught Error: Cannot use object of type stdClass as array in /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/types/vendor/toolset/types/embedded/includes/module-manager.php:308
Stack trace:
#0 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/types/vendor/toolset/types/embedded/includes/module-manager.php(425): wpcf_register_modules_items_types(Array, Array)
#1 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-includes/class-wp-hook.php(286): wpcf_register_modules_items_relationships(Array)
#2 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-includes/plugin.php(203): WP_Hook->apply_filters(Array, Array)
#3 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/toolset-module-manager/models/Modules.php(141): apply_filters('wpmodules_regis...', Array)
#4 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/toolset-module-manager/views/modules.php(152): ModMan_Modules_Model->getRegisteredItemsPerSection(Array)
#5 /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/pl in /Users/nigelanderson/OnTheGo/Sites/c-phuong/wp-content/plugins/types/vendor/toolset/types/embedded/includes/module-manager.php on line 308
One of the things I did was to update Types and Views to their latest versions, and that fixed the issue.