Fix E0193: Method Has an Incompatible Type for Trait in Rust

Thu, 06 Aug 2026 12:44:04 +0800

1. Symptoms

When the Rust compiler encounters error E0193, you will see an error message similar to the following in your build output:

error[E0193]: method `method_name` has an incompatible type for trait `TraitName`
  --> src/lib.rs:12:1
   |
12 |   fn method_name(&self) -> ReturnType {
   |   ^ expected `fn(&self) -> ExpectedType`, found `fn(&self) -> FoundType`
   |
   = note: expected due to the trait definition

The error manifests when implementing a trait method where the method signature diverges from the trait definition. You may observe the following indicators:

E0193 on ErrorVault — Developer Error Code Dictionary

Fix E0193: Method Has an Incompatible Type for Trait in Rust

1. Symptoms