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Published Jul. 2, 2025

"Invalid attempt to spread non-iterable instance" error when saving Instance Settings

Written By

Alfonso Crisci

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Issue

  • When working on a Liferay instance fronted by a web server, customers may experience the inability to save any changes in the Control Panel > Instance Settings sections. The attempt to save will fail with error Invalid attempt to spread non-iterable instance in the browser's console:

    mceclip0.png

    and, in the Network tab of the browser's developer console, an HTTP 405 error message will be thrown against the GET request to /o/dynamic-data-mapping-form-context-provider url:

    mceclip1.png

Environment

  • Liferay DXP 7.0+

Resolution

  • Ensure the ending forward slash / (/o/some-api/) isn't removed from the end of the URL by any webserver rules (for example, Apache httpd rewrite rules). If you are removing the ending forward slash due to SEO reasons, a possible approach to this is to modify the webserver rule not to remove the slash when the URL starts with /o/
  • Ensure the webserver does not block specific Liferay's GET requests

Additional Information

  • The ending forward slash / is part of the "identifier" of the REST API: removing it from the URL will result in the Liferay inability to find the API to execute
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