[zcash/zcash] Help users understand “transaction not mined” situations (#1959)

@tromer, to address your concerns, we are:

1. updating the answer to [ Are my funds safe during the transition?](https://z.cash/support/faq.html#safe-zcash-upgrade) to talk about transaction expiry. The updated text is as follows:

Are my funds safe during the transition?

If your wallet has upgraded, you don’t need to do anything to ‘transfer’ your money. For safe keeping of funds during any version upgrade and as a general practice, we highly recommend making and keeping regular backups of your wallet.
It is best practice to stop sending transactions near the network upgrade activation height; we recommend not sending transactions an hour or so beforehand. Transactions that are not mined before the activation height will need to be resent after the upgrade.
If you have sent a transaction after the upgrade and it has not been mined, wait for the transaction to expire (the transaction expiry period is about ~10 minutes/20 blocks) and try your transaction again. For understanding various situations and responses to unmined transactions, see this question.
2. adding another question to be put at the bottom of the “Zcash Ecosystem” section (first section, new question as last question).

What do I do if my transaction is not being mined?
After the Overwinter network upgrade, all transactions expire after ~10 minutes/20 blocks, and the best thing to do is to try your transaction again with some modifications. When your transaction expires, your funds will be returned to you.

There may be various reasons why your transaction is not included in a block:
– Loss of connectivity
– Transaction fee too low
– Network overload
– Too many transparent inputs (transaction size too large)

We suggest trying your transaction again with:
– Try again with a better connection
– Use the standard fee (0.0001 ZEC)
– Try again later, or increase the fee for high priority transactions
– Use a minimal amount of inputs to limit the size, or increase the fee for large transactions
For this question, we tried to address your original concerns, mentioned in your [first comment](https://github.com/zcash/zcash/issues/1959#issue-196982254), but we excluded “loss of connectivity to peer nodes” (it will error out, or just send; not be in limbo), “transaction mining priorities” (a possibility but zcash hasn’t experienced this as far as we know), “miners using stricter rules” (seems to be same as too many transaction inputs), and “anchor reorg” (uncommon/we didn’t know what to say).

We hope that adding additional information to the [FAQ page](https://z.cash/support/faq.html) will help users understand their transaction not mined situations.

This post was last modified on May 7, 2018, 11:02 pm