Android Studio updates have led to errors

Question

I just updated my Android Studio to the current 0.3.1 version. Consequently I've started getting a few issues that I can't seem to understand. First I get this message about problems with the plugin on launching Android Studio. The message is as follows:

Plugin Error
Problems found loading plugins: Plugin "Android Designer" was not loaded: 
required plugin "Android Support" is disabled. 
Plugin "Google Cloud Tools For Android Studio" was not loaded: 
required plugin "Android Support" is disabled.  
Disable not loaded plugins Enable Android Support Open plugin manager

The most worrying - which has essentially halted my progress at the moment - is that the IDE can't resolve XML files in the R.xxx. Such as this line:

  setContentView(R.layout.activity_lists);

It suggests I use android.R which brings up further errors due to incompatibility. I'm not sure how to fix this. On another occassion when this happened, further updates automatically resolved this issue.

Answer 1

In Android SDK Manager, select the following items and then click Install packages:

Extras/Google Repository

Extras/Android Support Repository

After install restart Android studio