I have mined coins that say "Not Accepted." How do I fix this?

It says "Status: conflicted, broadcast through 58 nodes
Date: 9/14/2017 05:37
Source: Generated
Debit: 0.00 BLK
Net amount: -494.54968333 BLK

Generated coins must mature 510 blocks before they can be spent. When you generated this block, it was broadcast to the network to be added to the block chain. If it fails to get into the chain, its state will change to "not accepted" and it won't be spendable. This may occasionally happen if another node generates a block within a few seconds of yours."

And the status says "Generated, Not Accepted."