Fix E0137: More Than One Trait Bound for Type

Fri, 24 Apr 2026 00:44:04 +0800

1. Symptoms

When you attempt to compile Rust code that specifies multiple trait bounds incorrectly for a single type parameter, the compiler halts with error E0137. This error manifests with a clear diagnostic message that identifies the problematic type and indicates that only one trait bound is allowed.

error[E0137]: more than one trait bound for `TypeName`
 --> src/main.rs:5:20
 |
5 | fn process<T: Clone + Display>(value: T) {}
 | ^^^^^^^ help: consider joining the trait bounds with a `+`: `Clone + Display`
 |
 = note: this error is being displayed to you because of user-facing `.into_iter()` calls
 = note: rustc 1.75.0 (firm version 3)

The compiler output explicitly points to the offending type parameter and shows the duplicate trait bounds. In most cases, the compiler helpfully suggests using the + operator to combine multiple trait bounds properly.

E0137 on ErrorVault — Developer Error Code Dictionary

Fix E0137: More Than One Trait Bound for Type

1. Symptoms