Currently (but not usually), if you call the following url you get an internal server error: https://api.linkedin.com/v1/people/~/connections:(id,headline,picture-url,summar
They seemed to have reduced the number of contacts you can get each time you request them. I used to ask for 500 and it worked for a long time, and then last week it stopped working and instead would return:
<status>500</status>
<timestamp>1424451457253</timestamp>
<request-id>HISKBDLSOA</request-id>
<error-code>0</error-code>
<message>Internal service error</message>
Now, I request 250 contacts each time and it works again.
https://api.linkedin.com/v1/people/~/connections:(public-profile-url)?start=0&count=250&modified=updated