Can't download or update apps [duplicate]

Solution 1:

1. First I'd suggest you to try perhaps thru an alternate internet connection.
2. If that doesn't resolve the issue I'd suggest you the following since you're stating that this happens every time you try to download an app or an update then I assume that this happens by every app and resetting your iPhone doesn't either work then I'd suggest you to try signing out of the App Store then restart your iPhone and sign into the App Store and try again to download.

See my answer in this post

Solution 2:

Usually this fixes itself server side in a day or three, but a way to triage this and ensure the device itself isn’t a problem is as follows.

1. Put the phone in airplane mode
2. Power down the device with no network (stay in airplane mode)
3. Open settings and record (paper or screenshot) how much free space is available after the restart (stay in airplane mode)
4. Pick an app you can delete, delete it, repeat the space measurement.

At that point you should know you have free space, the delete works and more space is returned.

Then power down the device a second time. When it restarts, confirm space is correct and then re-enable the networking.

At that point, you would either wait out the update error, find a new network entirely to check if the network were blocking updates, try restoring the device entirely after making a backup and/or ask Apple Store support to check your account.