After Upgrading from v15.30.2 => v15.31.0 Error: " {"exception":"[object] (GraphQL\\Error\\Error(code: 0): Config element \"String\" is not declared in GraphQL schema at "

[ECOPLANCOM]

In Magento 2 you get an error by running graphQL Queries after update ro v15.31.0
{"exception":"[object] (GraphQL\\Error\\Error(code: 0): Config element \"String\" is not declared in GraphQL schema at /var/www/share/XXX/releases/2026-03-16_08-12-13/vendor/webonyx/graphql-php/src/Error/Error.php:171) [previous exception] [object] (LogicException(code: 0): Config element \"String\" is not declared in GraphQL schema at /var/www/share/XXX/releases/2026-03-16_08-12-13/vendor/magento/framework/GraphQl/Config.php:57)"} [] [2026-03-16T07:30:40.265890+00:00] main.ERROR: Config element "String" is not declared in GraphQL schema

[marcoboom]

I'm having the same issue with the latest Magento patch upgrade.

[spawnia]

I am not familiar with what Magento is doing and I don't have time to look into it right now. For anyone who is willing, here is some context:

• Release: https://github.com/webonyx/graphql-php/releases/tag/v15.31.0
• Contained PR: Support per-schema scalar overrides #1869
• Issue that motivated the PR: Replace static variables and statically referenced types with instance based TypeRegistry #1424

Just glancing at the error, it makes sense that it is related to the release. For now, I recommend pinning 15.30.2.

A failing test case that reproduces the issue from Magento would be the first step towards getting this fixed.

[ruudk]

I'm also experiencing issues on input side:

Variable "$cityId" of type "ID" used in position expecting type "ID".

I'm currently debugging this to find the root cause of it and will report back.

[ruudk]

Possible solution: #1875

Fixed in #1876

[spawnia]

@ECOPLANCOM @marcoboom Can you try installing #1876 and check if that fixes your issue?

composer require webonyx/graphql-php:"dev-fix-built-in-scalars-comparison as 15.31.1"