I'm attempting my first Craft plugin and trying to update https://github.com/matthewattanasio/Craft-Url-Decoder-Twig-Extension for Craft 3 and followed the instructions in the docs for loading plugins which seemed to work in that the plugin appeared in the control panel, but I also got the following error:

[UnexpectedValueException] Package cakephp/core's source key should be specified as {"type": ..., "url": ..., "reference": ...}, {"type":"git","url":"https://github.com/cakephp/core.git","reference":null} given.

and now when I try to run any more composer commands I get the same error so I'm unable to do

composer remove package/name
composer require package/name

because I've made some changes to file names and need to update it.

The plugin is still showing in the CP but showing old information and when I try to install it, I get a server error.

1 Answer 1


The solution was to replace all references to "reference":null with "reference":"" in /craft/vendor/composer/installed.json.

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