Hey, let's break down your issue first — from the error logs and your build config, the root cause is clear: Gradle is trying to use a local proxy at 127.0.0.1:1088 to download build dependencies, but that proxy connection is being refused. This is why it can't fetch the kotlin-gradle-plugin and google-services artifacts it needs to configure the Android project, leading to the build failure.

Here are the most likely fixes you can try, ordered by simplicity:

1. Check your system proxy settings #

• First, make sure any proxy tool you might use is actually running and listening on port 1088. If you don't need a proxy right now, just turn off your system's global HTTP/HTTPS proxy and re-run the build. That should let Gradle connect directly to the Maven repositories.

2. Verify Gradle's own proxy configuration #

Gradle might have its own proxy settings separate from your system:

• Look for a gradle.properties file in your project root (create it if it doesn't exist) and check for lines like these:

  systemProp.http.proxyHost=127.0.0.1
  systemProp.http.proxyPort=1088
  systemProp.https.proxyHost=127.0.0.1
  systemProp.https.proxyPort=1088
  

• If you find these, either comment them out (add a # at the start of each line) if you don't need the proxy, or confirm your proxy service is running properly. Then try building again with flutter run or ./gradlew assembleDebug.

3. Switch to domestic Maven mirrors (optional, for network issues) #

If you're having trouble accessing Google or JCenter repositories directly even without a proxy, replacing them with domestic mirrors (like Alibaba's) can fix the problem. Update your android/build.gradle like this:

buildscript {
    ext.kotlin_version = '1.4.10'
    repositories {
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3'
    }
}

allprojects {
    repositories {
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }
    }
}

This will let Gradle fetch dependencies from faster, more accessible mirrors instead of the official ones.

Your build error log: #

FAILURE: Build failed with an exception.
* What went wrong: A problem occurred configuring root project 'android'.
> Could not resolve all artifacts for configuration ':classpath'.
> Could not resolve org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.10. Required by: project :
> Could not resolve org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.10.
> Could not get resource 'https://dl.google.com/dl/android/maven2/org/jetbrains/kotlin/kotlin-gradle-plugin/1.4.10/kotlin-gradle-plugin-1.4.10.pom'.
> Could not GET 'https://dl.google.com/dl/android/maven2/org/jetbrains/kotlin/kotlin-gradle-plugin/1.4.10/kotlin-gradle-plugin-1.4.10.pom'.
> Connect to 127.0.0.1:1088 [/127.0.0.1] failed: Connection refused (Connection refused)
> Could not resolve org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.10.
> Could not get resource 'https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin/1.4.10/kotlin-gradle-plugin-1.4.10.pom'.
> Could not GET 'https://jcenter.bintray.com/org/jetbrains/kotlin/kotlin-gradle-plugin/1.4.10/kotlin-gradle-plugin-1.4.10.pom'.
> Connect to 127.0.0.1:1088 [/127.0.0.1] failed: Connection refused (Connection refused)
> Could not resolve com.google.gms:google-services:4.3.3. Required by: project :
> Could not resolve com.google.gms:google-services:4.3.3.
> Could not get resource 'https://dl.google.com/dl/android/maven2/com/google/gms/google-services/4.3.3/google-services-4.3.3.pom'.
> Could not GET 'https://dl.google.com/dl/android/maven2/com/google/gms/google-services/4.3.3/google-services-4.3.3.pom'.
> Connect to 127.0.0.1:1088 [/127.0.0.1] failed: Connection refused (Connection refused)
> Could not resolve com.google.gms:google-services:4.3.3.
> Could not get resource 'https://jcenter.bintray.com/com/google/gms/google-services/4.3.3/google-services-4.3.3.pom'.
> Could not GET 'https://jcenter.bintray.com/com/google/gms/google-services/4.3.3/google-services-4.3.3.pom'.
> Connect to 127.0.0.1:1088 [/127.0.0.1] failed: Connection refused (Connection refused)
* Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 6s
Exception: Gradle task assembleDebug failed with exit code 1

Your android/build.gradle configuration: #

buildscript {
    ext.kotlin_version = '1.4.10'
    repositories {
        google() // Google's Maven repository
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:4.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.3'
    }
}

allprojects {
    repositories {
        google() // Google's Maven repository
        jcenter()
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

内容的提问来源于stack exchange，提问作者Zenko