Why am I seeing an error when I preview a Push Notification?
When you click Send Preview, we try to send the message to all users containing at least one registered test device. If the users have multiple devices, all of them should receive the push. See how to register a test device here.
"No push tokens exist for this device":
In some cases, some of those users may have some old and inactive devices associated with their profile, that may be missing a push token.
That is what triggers the warning, but nevertheless the push should send to the devices with a push token.
"Skipped message due to encountering a null template value."
This is caused because one of the Jinja expressions could assign a value and has to output null.
In such cases the message would not be sent for those users it happens to.
Check your personalization syntax, and make sure you provide a default value in case a certain attribute or expression is null. You can check our documentation for more details: https://docs.leanplum.com/docs/message-templating-#handling-missing-values