Hi,
Today I downloaded bitcoin core so I could receive money from someone.
You don't have to download only bitcoin core as there are light weight wallets like Electrum or multibit which could be used to receive bitcoins too.
About 45 minutes ago I provided the user who was sending the bitcoin with my receiving address.
He says it says pending and waiting for confirmation but on my bitcoin app theres nothing pending and balance is 0.
Sidenote: It says "Reindexing blocks on disk" 3 years 37 weeks.
I believe ,its reindexing database is probably converting the old database to the new one.That depends on your Internet speed for the amount of time taken.Took me couple of days to have the entire db reindexed.
Edit: he says its still pending but it was just confirmed.
Ask him for the transaction ID.Without the txid its not possible to check the actual status of the transaction.
1) Is the reindexing blocks the reason I haven't received the payment yet?
2) Could it be because he uses a different bitcoin app?
3) Is there any way to cancel a bitcoin transaction?
1->Maybe if you provide the transaction id ,we can see the status of the transaction.No,reindxing is not the reason you have received the payment.You might have received the payment but it would not reflect in your wallet address.Usually take around 4-5 hours with speed of 1mbps.
2->No doesn't matter,regardless of the bitcoin app,all transactions are public and appear on the blockchain.
3->If the transaction is unconfirmed,you can double spend it but that's not what you want to do. Theoretically,you can't cancel a transaction in your case because I'm sure it would have been confirmed by now.