My Icloud bastorage of 5 GB is full, howeer my Iphone storage still has 40 GB. why do i still get messages of unable to store photos.

Photos do not have to be synced with iCloud via iCloud Photos. However, if you don’t use iCloud Photos, your phots are included in the backup. I have 2,750 photos on my iPad Air and they take up 4GB of storage. Not all of them are included in the backup because some of them have been synced from my computer. My point is that if you have a whole bunch of photos and you backup with iCloud, you can quickly run out of iCloud storage.

Your options are,

1. Move some or all of the photos to a computer.
2. Delete some of the photos.
3. Don’t include photos in the backup.

Options 2 and 3 are not what I would recommend. I also recommend not using iCloud Photos without doing extensive research on what is involved.

Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

Looks like you answered your own question. You are right. Your iCloud storage capacity has 5GB. You have 40GB of space left on your iPhone. Your photos are being stored on your iPhone. The system is telling you that your photos cannot be backed up to iCloud because the size of the back up (including photos) is greater than 5GB. You data is still stored on your iPhone in its entirety however not backed up on iCloud.

Axel F.