The dependency types are actually case-sensitive.

docs/gettingstarted/modfiles.md

@@ -125,7 +125,7 @@ Mods can specify their dependencies, which are checked by NeoForge before loadin
 | Property       |  Type  |    Default    | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Example                                      |
 |:---------------|:------:|:-------------:|:---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:---------------------------------------------|
 | `modId`        | string | **mandatory** | The identifier of the mod added as a dependency.                                                                                                                                                                                                                                                                                                                                                                                                                           | `modId="jei"`                                |
-| `type`         | string | `"required"`  | Specifies the nature of this dependency: `"required"` is the default and prevents the mod from loading if this dependency is missing; `"optional"` will not prevent the mod from loading if the dependency is missing, but still validates that the dependency is compatible; `"incompatible"` prevents the mod from loading if this dependency is present; `"discouraged"` still allows the mod to load if the dependency is present, but presents a warning to the user. | `type="incompatible"`                        |
+| `type`         | string | `"REQUIRED"`  | Specifies the nature of this dependency: `"REQUIRED"` is the default and prevents the mod from loading if this dependency is missing; `"OPTIONAL"` will not prevent the mod from loading if the dependency is missing, but still validates that the dependency is compatible; `"INCOMPATIBLE"` prevents the mod from loading if this dependency is present; `"DISCOURAGED"` still allows the mod to load if the dependency is present, but presents a warning to the user. | `type="INCOMPATIBLE"`                        |
 | `reason`       | string |   *nothing*   | An optional user-facing message to describe why this dependency is required, or why it is incompatible.                                                                                                                                                                                                                                                                                                                                                                    |
 | `versionRange` | string |     `""`      | The acceptable version range of the language loader, expressed as a [Maven Version Range][mvr]. An empty string matches any version.                                                                                                                                                                                                                                                                                                                                       | `versionRange="[1, 2)"`                      |
 | `ordering`     | string |   `"NONE"`    | Defines if the mod must load before (`"BEFORE"`) or after (`"AFTER"`) this dependency. If the ordering does not matter, return `"NONE"`                                                                                                                                                                                                                                                                                                                                    | `ordering="AFTER"`                           |