Couldn't locate lint-gradle-api-26.1.2.jar for Flutter project

I solved the problem by moving:

maven {
    url 'https://dl.google.com/dl/android/maven2'
}

in the top of:

jcenter()

in the file: .flutter/packages/flutter_tools/gradle/flutter.gradle:

    buildscript {
    repositories {
        maven {
            url 'https://dl.google.com/dl/android/maven2'
        }
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

Modify flutter.gradle under ./flutter/packages/flutter_tools/gradle to upgrade the tools version to 3.2.1 and add google() to the first line:

buildscript {
  repositories {
    google()
    jcenter()
    maven {
      url 'https://dl.google.com/dl/android/maven'
    }
  }
  dependencies {
    classpath 'com.android.tools.build:gradle:3.2.1'
  }
}

Screenshot of my code

Regarding this error, I just changed this line in the build.gradle file:

classpath 'com.android.tools.build:gradle:3.1.2'

to:

classpath 'com.android.tools.build:gradle:3.1.3'

And that solved my problem.