gradle sync时sun.security.validator.ValidatorException

从星期一开始，我面临与sun.security.ValidatorException相关的问题 . 在上周一之前，每件事情都运转正常 .

例外情况是：
配置根项目'CoreApp'时出现问题 .

无法解析配置'：classpath'的所有文件 . 无法下载gradle.jar（com.android.tools.build:gradle:3.1.2）无法获取资源'https://jcenter.bintray.com/com/android/tools/build/gradle/3.1.2/ gradle这个-3.1.2.jar” . 不能HEAD'https：//jcenter.bintray.com/com/android/tools/build/gradle/3.1.2/gradle-3.1.2.jar' . sun.security.validator.ValidatorException：PKIX路径构建失败：sun.security.provider.certpath.SunCertPathBuilderException：无法找到所请求目标的有效证书路径无法下载sdk-common.jar（com.android.tools:sdk-common ：26.1.2）无法获取资源'https://jcenter.bintray.com/com/android/tools/sdk-common/26.1.2/sdk-common-26.1.2.jar' . 不能HEAD'https：//jcenter.bintray.com/com/android/tools/sdk-common/26.1.2/sdk-common-26.1.2.jar' . sun.security.validator.ValidatorException：PKIX路径构建失败：sun.security.provider.certpath.SunCertPathBuilderException：无法找到所请求目标的有效证书路径无法下载sdklib.jar（com.android.tools:sdklib:26.1.2 ）无法获得资源'https://jcenter.bintray.com/com/android/tools/sdklib/26.1.2/sdklib-26.1.2.jar' . 不能HEAD'https：//jcenter.bintray.com/com/android/tools/sdklib/26.1.2/sdklib-26.1.2.jar' . sun.security.validator.ValidatorException：PKIX路径构建失败：sun.security.provider.certpath.SunCertPathBuilderException：无法找到所请求目标的有效证书路径原因：无法找到所请求目标的有效证书路径

我的应用级别是：

apply plugin: 'com.android.application'
apply plugin: 'io.fabric'

android {
    compileSdkVersion 27
    buildToolsVersion '27.0.3'
    defaultConfig {

        applicationId "com.package.app"
        minSdkVersion 16
        targetSdkVersion 27
        versionCode 2000044
        versionName "4.1.1"
        multiDexEnabled true
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    dexOptions {
        preDexLibraries = false
        javaMaxHeapSize "3g"
    }
    packagingOptions {
        exclude 'META-INF/DEPENDENCIES.txt'
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/notice.txt'
        exclude 'META-INF/license.txt'
        exclude 'META-INF/dependencies.txt'
        exclude 'META-INF/LGPL2.1'
    }
    buildTypes {
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
repositories {
    mavenCentral()
}
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    //compile 'com.squareup.okhttp3:logging-interceptor:3.4.0'
    compile 'com.android.support:appcompat-v7:27.1.1'
    compile 'com.android.support:design:27.1.1'
    compile 'com.google.firebase:firebase-core:15.0.2'
    compile 'com.google.firebase:firebase-config:15.0.2'
    compile 'com.google.firebase:firebase-messaging:15.0.2'
    compile 'com.google.android.gms:play-services-tagmanager:15.0.2'
    compile 'com.google.android.gms:play-services-auth:15.0.0'
    compile 'com.google.android.gms:play-services-maps:15.0.0'
    compile 'com.google.android.gms:play-services-location:15.0.0'
    compile 'com.google.code.gson:gson:2.8.0'
    compile 'com.squareup.retrofit2:retrofit:2.1.0'
    compile 'com.squareup.retrofit2:converter-gson:2.0.2'
    //compile 'com.google.firebase:firebase-crash:12.0.1'
    compile 'com.crashlytics.sdk.android:crashlytics:2.9.2'
    compile 'com.facebook.android:facebook-android-sdk:4.31.0'
    compile 'com.appsflyer:af-android-sdk:4.8.9@aar'
    compile 'com.android.installreferrer:installreferrer:1.0'
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:multidex:1.0.3'
}
apply plugin: 'com.google.gms.google-services'

项目级别是：

buildscript {
    repositories {
        jcenter()
        google()
        maven {
            url 'https://maven.fabric.io/public'
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
        classpath 'com.google.gms:google-services:3.2.1'
        classpath 'io.fabric.tools:gradle:1.25.1'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
        google()
    }
}

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

我不知道是什么问题 . 请帮助我由于此错误而无法开发 .