Fix E0794: Invalid discriminant value for enum in Rust

Tue, 21 Jul 2026 22:20:04 +0800

1. Symptoms

When the Rust compiler encounters error E0794, you will see output similar to the following in your terminal:

error[E0794]: invalid discriminant value for enum `EnumName`, valid values are 0..2
  --> src/main.rs:10:17
   |
10 |     let _ = unsafe { transmute::<u8, EnumName>(3u8) };
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^ invalid discriminant value
   |
   = note: values are validated based on the enum discriminant type and defined variants

The error message specifies which discriminant values are considered valid for your enum, helping you understand the range of acceptable values. The compiler indicates the exact location in your source code where the invalid discriminant is being used, and it clarifies the bounds of valid discriminants based on the number of variants defined in your enum.

E0794 on ErrorVault — Developer Error Code Dictionary

Fix E0794: Invalid discriminant value for enum in Rust

1. Symptoms