Unity Google Mobile Ads安卓构建失败求助：错误异常及SDK调整后变更

Hey there, let's work through this issue step by step to get your game running smoothly again. It’s super frustrating when a working game suddenly breaks, especially with conflicting advice about SDK updates—let’s cut through the noise.

Step 1: Ditch the Android-P Preview SDK First #

Preview SDKs like Android-P are meant for testing new features, not stable development. Unity’s support for preview Android versions is often spotty, and this is likely the root cause of your changed errors after installing it. Here’s how to roll back:

• Open Android Studio, go to SDK Manager (Tools > SDK Manager).
• Under the SDK Platforms tab, uncheck the Android-P preview option and click Apply to uninstall it.
• Install a stable SDK version instead—stick to Android 10 (API 29) or Android 11 (API 30) unless your Unity version specifically requires a newer one.
• Head back to Unity, go to Edit > Preferences > External Tools, and double-check that your Android SDK path points to the root folder of this stable SDK.

Step 2: Verify Unity <-> Android SDK/NDK Compatibility #

Unity has strict compatibility requirements for Android SDK and NDK versions. Using mismatched versions will almost certainly cause build errors:

• Check your Unity version’s official compatibility docs (you can find this in Unity’s built-in help or release notes) to find the recommended SDK API level and NDK version.
• For example, Unity 2020.x typically works best with SDK API 29/30 and NDK r19 or r21. Make sure your installed SDK/NDK matches these recommendations exactly.

Step 3: Audit Your Build.gradle File #

Since you’ve shared your Build.gradle, focus on these critical areas to fix conflicts:

• compileSdkVersion and targetSdkVersion: Ensure both are set to the same stable API level you installed (e.g., 29 or 30). Never use a preview version number here.
• minSdkVersion: This should match the minimum Android version your game supports (e.g., 21 for Android 5.0+). Don’t set it higher than your compileSdkVersion.
• Dependency versions: Check all entries under dependencies for version conflicts. For example, if your compileSdkVersion is 29, use com.android.support:appcompat-v7:29.0.3 (match the SDK version). Avoid mixing old and new support libraries or Google Play Services versions.
• Plugin conflicts: Some Unity plugins inject their own gradle settings. Look for duplicate dependencies (like multiple versions of play-services) and remove the redundant ones, or force a consistent version using resolutionStrategy in your gradle file.

Step 4: Clear All Caches (They’re Often the Culprit) #

Corrupted cache files are a common cause of random build errors. Let’s wipe them out:

• In Unity:
  1. Go to File > Build Settings > Android, then click Clean Build.
  2. Go to File > Clear Cache to remove Unity’s build cache.
  3. Manually delete the Temp and Library folders in your Unity project directory, then restart Unity—this forces it to regenerate all project resources from scratch.
• In Android Studio:
  1. Go to File > Invalidate Caches....
  2. Select Invalidate and Restart to clear AS’s cached data.

Step 5: Fix the Root Error (Not Just the Chain Reactions) #

If you still get errors after the above steps, don’t panic—focus on the first error message in your console. Most subsequent errors are just side effects of the initial issue. For example:

• If you see "version conflict", use the gradle dependencyInsight command to track down which plugin is pulling in the conflicting version.
• If you see "missing SDK component", go back to Android Studio’s SDK Manager and install the missing package (e.g., build tools for your target API level).

内容的提问来源于stack exchange，提问作者alaslipknot