Android studio solves error: mouse not specified

When using Android studio for builder apks, if you find that you can’t degub,

No module can be specified during configuration, as shown in (borrow a figure)

The reason for the problem is that the grade files are not synchronized effectively.

1. First ensure grade Synchronization is complete.

2. Perform manual synchronization

Old as version   Click Tools – > Android—> Sync Project With Gradle Files

The new version (I am the new version) is shown in the figure:

Generally, you can debug, and the module has been configured