两个可能原因：
1、权限：
$ rm -rf pub/static/*
$ php bin/magento setup:static-content:deploy
2、When Magento 2 is not in production mode, it will try to create symlinks for some static resources on local server. We have to change that behavior of Magento 2 by going to edit ROOT > app > etc > di.xml file. Open up di.xml in your favorite code editor, find the virtualType name=”developerMaterialization” section. In that section below, you will find an item which needs to be modified. You can modify it by changing the following content:
MagentoFrameworkAppViewAssetMaterializationStrategySymlink
To:
MagentoFrameworkAppViewAssetMaterializationStrategyCopy
Now last step, also delete old files generated in ROOT > pub > static > DELETE ALL EXCEPT .HTACCESS
Clear / Flush Magento cache by typing “php bin/magento cache:flush” in CMD.
And finally, to Reindex Magento Static Blocks type “php bin/magento indexer:reindex”.
You are done with successful installation of Magento 2.
