After my Drupal 8.51 upgrade, I keep getting this error.

Uncaught PHP Exception Drupal\Component\Plugin\Exception\PluginNotFoundException: "The "ComplexData" plugin does not exist."

I have Googled it for two days and haven't found any information about what this is or how to fix it. I get the error while using Panels/Page Manager. I did upgrade both modules to the 4/14 release but that didn't help. Any ideas?

  • Have you rebuilt the cache?
    – Clive
    Apr 16, 2018 at 16:27
  • Yes, I have. And also updated modules and done database update Apr 16, 2018 at 18:18
  • How did you upgrade? Using composer or drush?
    – Eyal
    Apr 16, 2018 at 22:50
  • I upgraded with Composer. I am also noticing that I am getting this whenever I try to add a new taxonomy term, in addition to when I am working with pages and variants. Very puzzling. Apr 17, 2018 at 13:17

1 Answer 1


I read in another post where an OP wrote that Composer didn't put all the /core files in place, so he manually copied the /core directory and all its files and that solved a similar problem he was facing.

I tried that last night, manually copying the Drupal 8.51 /core folder into my local install. It fixed the problem. I then copied the files into production and all is well. Thanks to all who commented.

  • Composer didn't put all the /core files something seems wrong here..
    – Kevin
    Apr 18, 2018 at 13:47
  • Agreed. I'm now looking at that. Apr 18, 2018 at 13:48
  • If you are running OSX/Linux, ensure you have the latest version of Composer, as well as patch. With Homebrew on OSX, you can get the latest version with brew install gpatch. Not sure of the Linux equivalent but probably similar. Mine is currently GNU patch 2.7.6. Late last year I had issues with the newer version of Git and some issue with patch that I needed to update.
    – Kevin
    Apr 18, 2018 at 13:55

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