Users on the Android Issue Tracker report a SMS bug in Android 5.0 Lollipop running on a Nexus 4 and Nexus 5 which prevents them from sending SMS messages, according to Google the bug is also present in the Nexus 6. The bug appears to be limited to certain mobile operators, for now Vodafone Netherlands, India and Mobistar Belgium have been reported. The affected users are still able to receive SMS messages the issue is limited to sending, when they sent a SMS some users receive error code 38.
The bug seems to be affecting all users connecting to the network of the affected mobile operators, because users on Virtual Operators (which use the infrastructure of the affected mobile operators) complain about the same bug.
Update: The Dutch website Tweakers reports that they’ve receive a response from Google stating the bug also affects the Nexus 6 and that the company has stopped the updates to Android Lollipop on the affected mobile devices till the bug has been resolved.