Flutter error: Could not download bcprov-jdk15on.jar (org.bouncycastle:bcprov-jdk15on:1.56)

Question

I'm failing to run my first ever Flutter App. Getting the below error.

Launching lib\main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...
Resolving dependencies...
* Error running Gradle:
Exit code 1 from: 

D:\PROJECTS\softwareProjects\AndroidProjects\flutter_app_2\android\gradlew.bat 
app:properties:
Download https://jcenter.bintray.com/org/bouncycastle/bcprov-jdk15on/1.56/bcprov-jdk15on-1.56.jar


FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'android'.
> Could not resolve all files for configuration ':classpath'.
   > Could not download bcprov-jdk15on.jar (org.bouncycastle:bcprov-jdk15on:1.56)
Finished with error: Please review your Gradle project setup in the android/ folder.
      > Could not get resource 'https://jcenter.bintray.com/org/bouncycastle/bcprov-jdk15on/1.56/bcprov-jdk15on-1.56.jar'.
         > Response 304: Not Modified has no content!

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

Flutter doctor is not giving any problem output of flutter doctor:

Running flutter doctor...
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel beta, v0.1.5, on Microsoft Windows [Version 10.0.16299.309], locale en-IN)
[√] Android toolchain - develop for Android devices (Android SDK 27.0.3)
[√] Android Studio (version 3.0)
[√] Connected devices (1 available)

• No issues found!

Flutter Analysis gives some errors though!

Answer 1

At the time of posting, jCenter is/was having an issue serving certain artifacts. This gradle issue tracks progress on the fix, and bintray's status page has an entry for March 17, 2018 detailing the problem.

A temporary workaround is to use mavenCentral instead of jCenter (or at least use it first).

This can be done by changing the repositories gradle uses. Since this is an android project the convention seems to be using allprojects as follows:

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

---

UPDATE 2021:

JCenter has now been made read-only by the company that manages it, and should really not be used as it won't have the most recent version of artifacts. If you must use it, at least put it after any other repositories you are using.