iPhone photo crashes WordPress/Server

Hi,

Something strange has happened and I can not see to fix it.
Now everything is working fine, no issues after plugin updates or wordpress updates.
I have been able to upload photos into the Media Library perfectly fine until today.
I have just got an iPhone6 and taken some photos, now when I got home I went to upload them to my wordpress site just like normal. ie ie download my photos onto my PC using the iCloud automatically. I use my PC (Firefox Browser) and choose the photo off the PC to upload to my site. It then takes ages (2mins) and then I get a 500 Internal Server Error and my site has crashed and I also presume the server as after about 5 mins the site is back up and running, however the photo is corrupted on the server.
So I have tried this process 16 times now and each time the same thing using different iPhone taken photos, so I tried a non-iPhone photo and it uploads fine with no issues. Try again with an iPhone photo and again a 500 Internal Server Error

Does anyone knoiw why iPhone taken photos might cause errors in uploading?

Thanks