my iphone 6 has a error message when i connect it to the charger

Why not tell us what it says, we can't see from here.

What is the error message?

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There are 3 possibilities:

1. The cable is not a genuine Apple cable or an approved 3rd party cable
2. If it's an "official" cable it is damaged
3. There is dirt or moisture in the Lightning connector on the bottom of the phone - clean and inspect it with a bright light, magnifier, and toothpicks

The other (remote) possibility is the USB adapter you are using is counterfeit.

Standard troubleshooting would be to try a different cable and different adapter, except for 3, which is really what you should check first.

Lawrence has summarized the possibilities.

II'm having this same problem and I don't know what tO do. My phone is completely dead, and I be tried several charging blocks as well as cords.

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Read the rest of the messages in this thread.

LizArena12 wrote:

II'm having this same problem and I don't know what tO do. My phone is completely dead, and I be tried several charging blocks as well as cords.

All the above still apply. If the phone is older and it was allowed to discharge completely, the battery may have gone over the threshold where charging is still possible and is now irrecoverably dead, thus needing a replacement. Best or only bet in diagnosing that is to take it to a Store or a service provider for assessment.