I can download or update apps

Check ⤵️

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone – Apple Support (UK)

Prevent in-app purchases from the App Store

Prevent in-app purchases from the App Store – Apple Support (UK)

If you can't connect to the App Store, iTunes Store, or other Apple services

If you can't connect to the App Store, iTunes Store, or other Apple services - Apple Support

-> If you tried all of the above steps and you still can’t connect, contact Apple Support.

Check also ⤵️

1.

If you can't make purchases or update / download apps, including free apps, you need to update your payment method or add a new one. 

See also the following Apple articles:

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

Add money to your Apple ID balance

Add money to your Apple Account balance – Apple Support (UK)

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

 If you're still unable to update your payment method, Contact Apple Support.

Click here for more support and assistance.

2.

If your payment method is declined in the App Store or iTunes Store

If your payment method is declined in the App Store or iTunes Store - Apple Support

⤵️

Get more help

• If you disputed a charge from the App Store or iTunes Store, contact your financial institution again to authorize that charge and future purchases from the App Store or iTunes Store.
• If you're outside of the United States, you might need to contact your financial institution to allow international purchases.
• In some countries and regions, your payment method might be declined because of changes to local law. Learn about billing and purchases in Europe or what to do if your card is declined in India.
• If you still need help, contact Apple Support.

3.

If your Apple ID is locked or disabled

If your Apple ID is locked or disabled - Apple Support (CA)

-> Get a verification code and sign in with two-factor authentication

Get a verification code and sign in with two-factor authentication - Apple Support

4.

If you see a message that says "Your account has been disabled in the App Store and iTunes", contact Apple Support for help.