Recently I installed Magento 2.1.3. The problem is that, when i am in the Component Maganer, and i Sync my account, it showns an infinite “please wait” loading, and i can’t install any extension at all.

After some research and searching I found one solution as below.

Please open your composer.json file and move to “repositories” section, and left only one repository, like shown below.

Before:

"repositories": {
        "0": {
            "type": "composer",
            "url": "https://repo.magento.com/"
        },
        "data-migration-tool": {
            "type": "git",
            "url": "https://github.com/magento/data-migration-tool"
        }
}

After:

"repositories": [
        {
            "type": "composer",
            "url": "https://repo.magento.com/"
        }
]

Modifying “repositories” in composer.json fixed this issue for me.