# How to Downgrade Transitive Dependencies in Gradle

version 9.0.0

This guide explains how to downgrade transitive dependencies in Gradle when your project requires an older version due to API compatibility, bugs, or other constraints.

## Why Downgrade a Transitive Dependency?

By default, Gradle resolves dependency version conflicts by selecting the latest version found in the dependency graph. However, there are cases where an earlier version is required:

- A bug exists in the latest release.

- Your project depends on an older API that is incompatible with newer versions.

- Your code does not require the features that demand a higher version.

Before downgrading, consider updating your source code to support the latest version instead.

Additionally, you should make sure there aren’t existing dependency constraint, platforms, or version catalogs, that are setting the dependency to an undesired version in your project.

If downgrading is necessary, use strict dependencies or forced dependencies.

## Option 1: Enforcing a Strict Version of a Dependency

Gradle allows you to enforce a strict version for a dependency, ensuring that the selected version cannot be upgraded by transitive dependencies.

### Step 1: Setting a Strict Version

Suppose a project depends on HttpClient, which pulls in Commons Codec 1.10, but your project requires Commons Codec 1.9:

dependencies.out

    > Task :dependencies

    ------------------------------------------------------------
    Root project 'how_to_downgrade_transitive_dependencies'
    ------------------------------------------------------------

    runtimeClasspath - Runtime classpath of source set 'main'.
    +--- org.apache.httpcomponents:httpclient:4.5.4
    |    +--- org.apache.httpcomponents:httpcore:4.4.7
    |    +--- commons-logging:commons-logging:1.2
    |    \--- commons-codec:commons-codec:1.10
    \--- commons-codec:commons-codec -> 1.10

You can enforce the required version by setting a strict version constraint:

build.gradle.kts

    dependencies {
        implementation("org.apache.httpcomponents:httpclient:4.5.4")
        implementation("commons-codec:commons-codec") {
            version {
                strictly("1.9")
            }
        }
    }

build.gradle

    dependencies {
        implementation("org.apache.httpcomponents:httpclient:4.5.4")
        implementation("commons-codec:commons-codec") {
            version {
                strictly("1.9")
            }
        }
    }

Running `./gradlew dependencies --configuration runtimeClasspath` showcases the results:

dependencies-downgrade.out

    > Task :dependencies

    ------------------------------------------------------------
    Root project 'how_to_downgrade_transitive_dependencies'
    ------------------------------------------------------------

    runtimeClasspath - Runtime classpath of source set 'main'.
    +--- org.apache.httpcomponents:httpclient:4.5.4
    |    +--- org.apache.httpcomponents:httpcore:4.4.7
    |    +--- commons-logging:commons-logging:1.2
    |    \--- commons-codec:commons-codec:1.10 -> 1.9
    \--- commons-codec:commons-codec:{strictly 1.9} -> 1.9

Important notes about strict versions:

- A strict version behaves like a force, meaning it overrides transitive dependencies.

- If another dependency requires a higher version, Gradle will fail with a resolution error.

- Use version ranges instead of absolute strict versions to allow flexibility.

### Step 2: Setting a Strict Version Range

Instead of locking to a single version, define a strict range:

build.gradle.kts

    dependencies {
        implementation("commons-codec:commons-codec") {
            version {
                strictly("[1.9,2.0[")  // Allows versions >=1.9 and <2.0
                prefer("1.9")  // Prefers 1.9 but allows newer versions in range
            }
        }
    }

build.gradle

    dependencies {
        implementation("commons-codec:commons-codec") {
            version {
                strictly("[1.9,2.0[")  // Allows versions >=1.9 and <2.0
                prefer("1.9")  // Prefers 1.9 but allows newer versions in range
            }
        }
    }

If another dependency requires 1.10, Gradle can resolve it without failure, as long as it falls within the specified range.

dependencies-extra.out

    > Task :dependencies

    ------------------------------------------------------------
    Root project 'how_to_downgrade_transitive_dependencies'
    ------------------------------------------------------------

    runtimeClasspath - Runtime classpath of source set 'main'.
    +--- org.apache.httpcomponents:httpclient:4.5.4
    |    +--- org.apache.httpcomponents:httpcore:4.4.7
    |    +--- commons-logging:commons-logging:1.2
    |    \--- commons-codec:commons-codec:1.10 -> 1.9
    \--- commons-codec:commons-codec:{strictly [1.9,2.0[; prefer 1.9} -> 1.9

## Option 2: Forcing a Version at the Configuration Level

If a strict dependency is too restrictive, you can force a specific version for an entire configuration using `resolutionStrategy.force()`.

### Step 1: Forcing a Version for the Entire Build

build.gradle.kts

    configurations {
        compileClasspath {
            resolutionStrategy.force("commons-codec:commons-codec:1.9")
        }
    }

    dependencies {
        implementation("org.apache.httpcomponents:httpclient:4.5.4")
    }

build.gradle

    configurations {
        compileClasspath {
            resolutionStrategy.force("commons-codec:commons-codec:1.9")
        }
    }

    dependencies {
        implementation("org.apache.httpcomponents:httpclient:4.5.4")
    }

Running `./gradlew dependencies --configuration compileClasspath` showcases the results:

dependencies-config.out

    > Task :dependencies

    ------------------------------------------------------------
    Root project 'how_to_downgrade_transitive_dependencies'
    ------------------------------------------------------------

    compileClasspath - Compile classpath for source set 'main'.
    \--- org.apache.httpcomponents:httpclient:4.5.4
         +--- org.apache.httpcomponents:httpcore:4.4.7
         +--- commons-logging:commons-logging:1.2
         \--- commons-codec:commons-codec:1.10 -> 1.9

This ensures that Commons Codec 1.9 is always used, even if transitive dependencies request a newer version.

## Summary

To review the two options:

Approach | Behavior
--- | ---
1. Strict version (`strictly()`) | The version is enforced but can trigger resolution failures if conflicts exist.
2. Forced version (`force()`) | The version is forcibly applied at the configuration level, overriding all other constraints.

In summary:

- Use strict versions if you need to enforce an older version and want to control compatibility.

- Use version ranges with a preferred version to allow some flexibility.

- Use `force()` at the configuration level when you need to override transitive dependencies without strict constraints.