Most likely, you need to upload this to Jive first to get a URI that is local. Try this before you do your place Avatar update:
curl -i -u user:pass -X POST -F "file=@your_file.jpg;type=image/jpg" "https://your_jive_instance/api/core/v3/images"
Per the docs here:
check for status code 201, and look at header: Location for the URL of the Jive image.
Then use that URL in your script above.
Note: I know you are using PHP over cURL (and not curl natively), but the above example should give you the pieces you need to translate into your library.
Hope this helps.
i have followed the steps you described above to set an avatar to a place using a Java Rest client but even though my file is successfully loaded on my Cloud instance i am still getting an 400 when calling the API via /places/placeID/avatar with Jive URL like MY_DOMAIN/api/core/v3/images/40068?a=1421772837116
Any idea why?
Were you able to update the avatar image?
I am facing the similar issue while uploading the image.