Upgrade from Rasp Pi 3 B+ to Rasp Pi 4 question

[townshendlights]

It looks like I have to replace my Rasp Pi 3 B+ with a Rasp Pi 4. 
My question is can I just take the SD card from my old pie and insert it in the Pi4 and will it just work? Or do I need to reinstall FPP?

[JonD]

It will the other way, so see no reason why it would not work.  I downgraded the PIs in my K8Pi from Pi4 to Pi3b+ and just swapped the cards no issues.  It is the same image for both systems.

[rayster]

So why the upgrade? Do not forget the fan and heatsinks since Pi4 run hotter then pi3.

[townshendlights]

So why the upgrade? Do not forget the fan and heatsinks since Pi4 run hotter then pi3.

I'm getting the lower power error and it stops playing videos on my VM. I'm using the official power supply.

[tbone321]

If you have anything connected to the PI's USB ports, it may be drawing more power than the "official power supply" can output.  I would try getting a larger power supply first and it won't go to waste since the PI4 needs a bigger power supply than the PI3 anyway.

[townshendlights]

If you have anything connected to the PI's USB ports, it may be drawing more power than the "official power supply" can output.  I would try getting a larger power supply first and it won't go to waste since the PI4 needs a bigger power supply than the PI3 anyway.

When you say larger, do you mean amperage or wattage? I'm not wanting to go over the 5.1v

[tbone321]

You don't want to up the voltage, that could damage the PI.  You want a power supply with a higher current output which is a higher wattage at 5V.

[townshendlights]

Update
I managed to stop the videos from freezing. I re-rendered them in DaVinci as  1280x720 and then optimized them in Handbrake to take them from hundreds of MB to under 20Mb each and now the pie plays them no problem.

So if anyone else has this problem, check the file sizes. As for the power error. As long as it's going, I'm not going to worry about it.

I do have one more issue with the projector output, but I'll start another thread so it doesn't hijack this one.