Regression Bug: Error "The type of this node cannot be serialized because its property '[fooSymbol]' cannot be serialized." happens but potentially avoidable automatically. #60114

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1. Ryan Cavanaugh (RyanCavanaugh)

   added

   Needs InvestigationThis issue needs a team member to investigate its status.This issue needs a team member to investigate its status.

   on Oct 2, 2024
2. Ryan Cavanaugh (RyanCavanaugh)

   assigned

   Wesley Wigham (weswigham)

   on Oct 2, 2024
3. Ryan Cavanaugh (RyanCavanaugh)

   added this to the TypeScript 5.7.0 milestone on Oct 2, 2024
4. caeus commented on Nov 1, 2025

   

   caeus

   on Nov 1, 2025

   More actions

   Still happening in 5.9.2 in similar cases, but only if compilerOptions.declararion is set to true

   👍React with 👍1Reacted by Voltra
5. Voltra commented on Mar 9, 2026

   

   Voltra

   on Mar 9, 2026

   Last edited by Voltra

   More actions

   In my case, in 5.9.3, I get that error even when compilerOptions.declaration is not set (or explicitly set to false).

   It looks like it's trying to "serialize" an array/tuple type as an object (with its methods as properties, etc.) instead of treating it as an array/tuple.

   TS4118: The type of this node cannot be serialized because its property [iterator] cannot be serialized.

   TS4118: The type of this node cannot be serialized because its property [unscopables] cannot be serialized.

   These warnings come from trying to "serialize" the type of the deeply nested property below from an as const object (needed for inference):

   export const DATA = {
     // [...]
     {
       "enum": [
           0,
           1,
           2
       ],
       "type": "number",
     },
     // [...]
   };
   
   export default DATA;

   Same with with:

   export const DATA = {
     // [...]
    {
       "required": [
             "id",
             "items",
             "name",
             "status"
         ],
         "type": "object"
     },
     // [...]
   };
   
   export default DATA;