Issues adding Mender to 2018-04 raspbian lite

What about older raspbian images?
For example, I’m experiencing issues adding Mender to 2018-04 raspbian lite. It works just fine of RaspberryPi 3B, but RaspberryPi 3B+ can’t boot, I’m getting this sequence running from freshly burned image generated with mender-convert:
rainbow screen -> screen with raspberries but without any output for couple of seconds -> reboot > rainbow screen forever.

Where to look for a fix (if updating to a newer raspbian is not an option)? FIY, all newer versions of raspbian lite work fine.

We have never tested 2018.04 images.

To further debug any issues I would suggest to capture the output on the serial console, that might provide an hint of what is going on.

Edit: Also make sure you are running the latest version on 1.1.x branch of mender-convert which has a fix to a similar problem to what you describe.

Pulling latest version of mender-convert git resolved the issue, thanks for pointing out!