JetBrains/intellij-community · error · EvaluateException

Cannot substitute ''{0}'' into ''{1}'' as ''this''

Error message

Cannot substitute ''{0}'' into ''{1}'' as ''this''

What it means

Error "Cannot substitute ''{0}'' into ''{1}'' as ''this''" thrown in JetBrains/intellij-community.

Source

Thrown at java/debugger/impl/src/com/intellij/debugger/ui/impl/watch/DebuggerTreeNodeExpression.java:93

          }
        }
        else if (type instanceof PsiArrayType && PsiUtil.isArrayClass(thisClass)) {
          castNeeded = false;
        }
      }
    }

    if (castNeeded) {
      howToEvaluateThis = castToRuntimeType(howToEvaluateThis, howToEvaluateThisValue);
    }

    ChangeContextUtil.encodeContextInfo(result, false);
    PsiExpression psiExpression;
    try {
      psiExpression = (PsiExpression)ChangeContextUtil.decodeContextInfo(result, thisClass, howToEvaluateThis);
    }
    catch (IncorrectOperationException e) {
      throw new EvaluateException(
        JavaDebuggerBundle.message("evaluation.error.invalid.this.expression", result.getText(), howToEvaluateThis.getText()), null);
    }

    try {
      PsiExpression res = JavaPsiFacade.getElementFactory(howToEvaluateThis.getProject())
        .createExpressionFromText(psiExpression.getText(), howToEvaluateThis.getContext());
      res.putUserData(ADDITIONAL_IMPORTS_KEY, howToEvaluateThis.getUserData(ADDITIONAL_IMPORTS_KEY));
      return res;
    }
    catch (IncorrectOperationException e) {
      throw new EvaluateException(e.getMessage(), e);
    }
  }

  public static final Key<Set<String>> ADDITIONAL_IMPORTS_KEY = Key.create("ADDITIONAL_IMPORTS");

  public static PsiExpression castToRuntimeType(PsiExpression expression, Value value) throws EvaluateException {
    if (!(value instanceof ObjectReference)) {

View on GitHub (pinned to be881553f2)

Solutions

1. Use an expression whose type is assignment-compatible with the required 'this' type in that context.
2. Qualify the reference explicitly instead of relying on 'this' substitution.

Example fix

Write 'otherObject.field' instead of relying on substituting 'this' for an unrelated type.

When it happens

Trigger: A debugger tree expression tries to substitute a value of an incompatible type as 'this'.

Common situations: Custom renderers or expression nodes built for one type being applied to an object of another type.

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/4a6ada63ba06b07c. Report an issue: GitHub.