iPhone error 27 during iTunes update

Thanks for the quick response. I tried the suggestions but none get me out of my fix. I beginning to think it really is a hardware issue.

The "plug in to iTunes" screen that started these errors has appeared on my iPhone4 about 10 times in the past few weeks when I let the battery charge drop to a low level. The screen went away if I simply left the phone on the charger for a few hours. An overnight charge lasts only a day with moderate use so the battery is certainly wearing out. Today the "plug in to iTunes" screen did not go away with charging so I plugged in to iTunes on my PC and started this endless Error 27 cycle.

I still suspect the battery. I'm going to let the phone discharge for a day or two and try another recharge. I have other old GSM phones from the kids so I can move the SIM card. iCloud.com has backup data except photos which iCloud Photo says can't be backed up from iOS7.

I haven't tried the iTunes "Restore" yet because it looks like it will wipe all photos including the last few weeks which I failed to copy elsewhere.

I will let you know what happens.

My iPhone4 is back online.

I must first admit that I did not immediately reload iTunes when the error started happening because I was worried that the backup information stored previously by iTunes on my PC would be lost.

So there I was with the original iTunes supposedly downloading an update, waiting for iPhone, the apple and a progress bar appearing on the phone, more delay and eventually iTunes giving up. I closed iTunes to try again. I tried to restart iTunes but nothing would happen. I opened the Windows Task Manager and there was iTunes, still running with associated tasks. I used Task Manager to shut it down and I could start iTunes again. This time I asked for a restore and I got to the same place with Error 27, an apple and stuck progress bar on the phone and iTunes "Waiting for iPhone". I stopped the invisibly running (stuck?) iTunes in Task Manager.

I opened Windows Apps > Uninstall to see my options for iTunes. I could Repair or Reset. I tried "Repair" which did nothing and I ended up with the same stuck iTunes and no-progress phone. When I tried "Reset" I was surprised as Windows uninstalled iTunes. Since I now had nothing to lose I re-installed iTunes from the Apple site.

I started up again with the new iTunes and I don't remember if I picked Update or Restore for my iPhone but now things were very different. iTunes spent a lot longer downloading the update and when the apple symbol and progress bar appeared on the iPhone the bar showed progress. When the bar completed my phone was back, pictures and all, except for the last three weeks since my last iTunes backup.

Apparently iTunes does not destroy old iPhone backups when a new iTunes version is installed. iTunes even pulled in my Notes files from my non-Apple email address. This is a great argument for Apple software.

iTunes suggested I use iCloud for automatic, timely, future backups and I immediately switched.

I also switched over two relatives who were still using the iTunes backup.

In short, if you see Error 27 in iTunes iPhone updates on Windows don't be afraid to remove and re-install iTunes.

You gave me the correct solution the first time.

Thanks!