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error:Connection reset (Gradle sync failed: Connection reset)

I am importing constraint-layout-start to android studio 3.0. I have kept in androidstudioproject folder that's the the path where all my android studio projects are stored. after importing its showing connection reset error. Here is the log file link: https://drive.google.com/file/d/1W1mGmIc67baZb4C5nGGecWm15ggB0Wp5/view?usp=sharing
i have all the SDK installed. tried to manually change the sdk verion to 21 which was running perfectly for my other projects, but here it didn't work.
i checked all the files are okay, i am not getting why this error occurs.
images of gradle page are given below.
build.gradle
gradle

Add google repository to your gradle file:
repositories {
maven()
//other repositories...
google()
}
Try to download from SDK manager:
SDK Manager Android Studio
Check your gradle and plugin version:
https://developer.android.com/studio/releases/gradle-plugin.html#updating-gradle

For Android studio 3.0.0
required Gradle version: 4.1
File > Project Structure > Project
required Build Tools 26.0.2

For Android Studio 3.4 Canary 8
Hope it will helpful!
Go To File>Settings>Build, Execution, Deployment>Gradle
and set your Android studio local gradle path like below image

i solve this problem in this way. be careful it causes with different problems like using proxy, dns connection windows , fire wall block , ....
anyway, i use proxy in file/settings/proxy in android studio and after that i set no proxy. after that whenever use kerio vpn or cisco gradle didnt work.
solution :open gradle.properties and remove every proxy script from there and sync gradle and work fine

Cannot run my app, asking to select Android SDK

Today I've installed Android Studio Canary 1
Now I cannot run my app. This following dialog appears.
I've already set the right SDK location through File-> Project Structure-> Android SDK location.
Expecting your help to solve this problem.
Warning Dialog image:

Go to project structure settings and set Source Compatibility and Target Compatibility to your current java development kit version:

Just you need to sync your project file with your gradle file.
File -> Sync Project with Gradle Files

I tried every answer in this post but my problem only got resolved when I made these steps:
File -> Close project -> Remove project -> Open existing project (same
project)
Maybe this will save a morning to another person with the same bug.
EDIT
This happened to me a lot on a MacBook. After I posted this answer it just kept happening so what I did was:
uninstall the Android Studio version I had from the App Store;
download the desktop stable version from Android Studio website;
start using the desktop version of Android Studio.
Never happened again.

Sometimes the SDK path will be incorrectly configured. You would need to fix it.
To Settings/Preferences( command + , on mac).
Search for SDK
Under Android SDK, click on edit and point it the root of sdk directory on your file system. (If ther is no SDk installed then install in from the below list).

i suggest you go to build.gradle and sync again.
Or Tools -> Android -> Sync Project with Gradle Files (Android 3+)

You need to insall SDK api 19 check this out.
https://developer.android.com/studio/releases/platforms

Go to sdk manager and install sdk according to your device and check your device api. Example if your device is jellybean then install api 19 sdk.

Go to Tools> Android > SDK Manager and make sure you have selected default Setting under System Setting. In this image I have selected Android 7.1.1 as default SDK

Just click on the button ..."Sync Project with gradle file"
Error will be remove

I had the same problem and what it worked for me was just sync with gradle.
I just did what I've found in this similar question:
How do I "select Android SDK" in Android Studio?
The original answer:
go to build.gradle and click sync now. Then it worked.
Update :
File -> Sync Project with Gradle Files (Android Studio 3.1.1)
Tools -> Android -> Sync Project with Gradle Files (Android Studio
3.0.1) Or You can click on the icon from the toolbar.
Sync Project Icon
This answer may not help works for later version as Android studio Team work on making the tool more better, the way to sync may be
different in the next version of Android Studio.
COMMON WAY that may helps is try to sync project and then Invalidate
Caches and Restart Android Studio.
Solution for Android Studio 3.1.2
Before that, by the way, I had invalidated cache and restarted too, but it didn't work.
Please, try and let us know.
P.S.
I had this problem after I imported a project from Git, just in case someone would like to replicate.

Android studio 2.3 refreshing gradle project taking forever

I updated my android studio to the new version 2.3 and was asked to convert my project to match the new formats which I did. I was asked to update the gradle version too and I did. Now one eternity later it's still refreshing my project gradle. I've restarted it several times and I have active internet connection. Any suggestions

This method works for Me :
Change Gradle Home Path as C:\Program Files\Android\Android Studio\gradle\gradle-3.2
To Open Gradle Home Setting :
Settings->Build,Execution,Deployment->Gradle->Gradle Home

It depends sometimes on what are you building. As Hamid said, it´s a must do working Offline, it greatly reduces times, or at least it did not that long ago.
Also checkout that you are not building google APIs that you are not using, be careful with google's play-services or maps, they sometimes take a bunch of time and maybe you are not using them.
If that's an option, install Android Studio in a SSD, don't buy one, but if you have it, consider moving it, it reduced my gradle about 90%.
Also, check this, a bit old, but may help.

Could be caused by Microsoft Defender.
Check if msmpeng.exe is running in task manager
and exclude Android directory.

using default gradle wrapper and disconnecting from my corporate network to a 4G network solved my problem

File> Settings> Build, Execution, Deployment> Gradle> and check the Offline work

If you have an failed for sync gradle. Such as; Gradle sync failed: Minimum supported Gradle version is 3.3. Current version is 3.2.
Download Gradle supported version manually.
Uncheck "Use default gradle wrapper (recommended)"
Check "Use local gradle distribution" and set Gradle home path.
Check offline work.

Updating the gradle path in
File > Settings > Build, Execution, Deployment > Gradle
worked for me. The problem occured after updating Android Studio.

Gradle error: Write access is allowed from event dispatch thread only in Android Studio

After updating Android Studio to version 2.2 (on Windows 10) and somehow next morning I received such error when gradle built on any project:
Write access is allowed from event dispatch thread only
Despite that gradlew -build command worked and completed successfully.
I tried typical Android dev's of WTF repairing set: clean build, invalidate caches, removing build folders, removing .gradle folder, tried different gradle settings, even reinstalling Android Studio and nothing helped.
I've created this question only to share my experience with community, because I wasted two hours on it.

So the problem was concluded in that Android Studio conflicted with my installed JDK version, so it was resolved when I checked JDK location (File → Project Structure → SDK Location), ticked 'Use embedded JDK' checkbox and set JDK location to 'path to Android Studio'\Android Studio\jre

Problem was occurred when android studio conflict with installed jdk
version, Go to the (File -> Project Structure -> SDK Location), check
'Use embedded JDK' checkbox and set jdk location to 'path to android
studio'\Android Studio\jre :) Simple

that didn't work for me, i ran a 'gradle clean build' command, i figured out that there's a conflict in a line in the gradle, deleted it and sync project (as in this pic)

My issue was that I had removed the SDK I was using while clearing up hard drive space.
To fix this, first check what SDKs you have installed, or install one in Tools > SDK Manager.
You can then change the compileSdkVersion and targetSdkVersion in app build.gradle to your installed sdk version.
Otherwise you can just reinstall what ever sdk you were using.

In Android Studio 3.2.1 go to File -> Project Structure -> SDK Location and check in the check box "Use embedded JDK (recommended)".

How to successfully sync in Android Studio?

Version Info:
Android Studio -- 0.8.0
Gradle -- 2.0
Issue: When open Android Studio, the following information displays, hence it is not able to run the program.
Error:No cached version listing for com.android.tools.build:gradle:0.12.+ available for offline mode.

From : https://stackoverflow.com/a/24106285/1239966
Uncheck "Offline work" in File>Settings>Gradle>Global Gradle Settings
Resync the project, for example by restarting the Android Studio
Once synced, you can check the option again to work offline.