Same problem. I tried all the tricks found on internet last night, including the exact same ones posted here and even chatted with tech support. I can still download a few simpler, smaller apps but not the ones I want which are larger and have been recently upgraded. I have come to the conclusion that my iPad 4 is becoming "obsolete", sad to say, and although it will still work with the apps we already have, we can't get new versions of some apps, nor download newer versions apps much less ger. I bought my iPad in 2012, so it's almost 7 years old. Internet info suggests i should recognize that it's lived a long good life and is ready to retire. I still love it and will use it as long as I can!
