What changed in ElectrumSV 1.4.0b1?

By The ElectrumSV Developers

Remember that this is a beta release. It is already well tested, and very likely to be what we release in the 1.4.0 release. Any wallet you update or create with this will be fully supported in future releases. And yes, we do back up your wallet when you update it. Please report any bugs you experience so we can fix them.

The highlights

These are the most important changes in this new version of ElectrumSV. It is by no means all the changes that are included in this release, just the most important for you to learn about.

Declaring what payments you expect to receive

The largest part of this release, is that ElectrumSV no longer monitors the blockchain anywhere near as much as it used to. If you expect to receive an incoming payment, you need to use the user interface to declare that you expect it first. If you don't, ElectrumSV will not know about it.

The "Receive" tab where incoming payments are created and viewed.

The "Receive" tab where incoming payments are created and viewed.

You can read our guide on how to receive payments in our documentation.

Looking on the blockchain for payments you do not have

There are still at least two cases where ElectrumSV needs to look on the blockchain for payments to an account in one of it's wallets. The most important case is wallet restoration. If someone creates an account using their existing seed words, one of the first thing they will want to do is find all the transactions relating to that account. Another case that it is important ElectrumSV handles, is to look for missing transactions in the case of error whether on the part of the wallet or the user. For this reason, we have added the blockchain scanner.

The "Blockchain scanner" dialog used to find payments on the blockchain.

The "Blockchain scanner" dialog used to find payments on the blockchain.

You can read our guide on how to scan the blockchain in our documentation.

Complete historical mainnet headers

We bundle all mainnet headers up to a recent height with this release. This is a change from the existing approach where we had checkpoints and only fetched and backfilled headers as we needed them. This prepares us for supporting SPV in the future.

Note that this comes with costs:

  • Download sizes are 40 megabytes larger.
  • Startup will be several seconds slower, and because the application creation tool that we use, PyInstaller, is already slow this may be especially noticeable.

New problems for MacOS users

Unfortunately, Apple have broken the way we distribute applications. When Apple users start up ElectrumSV they will see the following misleading error and will not be able to run it.

The buggy MacOS "your application is not signed" dialog.

You can read our guide on MacOS issues and ways to work around them in our documentation. We will attempt to fix this before we release the final polished 1.4.0 release we eventually make.

The details

Codebase upgrade

When the ElectrumSV project began, the software it inherited had a range of technical limitations. These ranged from loading all wallet data into memory when a wallet was opened, and writing it all out when it was saved. To potentially adding and deleting transactions to the user's wallet every time they changed server.

With the 1.3.0 release we switched over to the use of a database for wallet storage, and solved the "load all data" issue. But we didn't have time to rewrite things like the blockchain synchonisation code that could delete a transaction the user just signed, because the server they switched to had incompatible settings. This meant that the 1.3.0 release, whose purpose was really primarily multi-signature transaction support, treated it's usage of database storage as an interim step towards a later ideal.

Making the database authoritative

A core goal with the 1.4.0 work was making the database layer enforce consistency for wallet data. This required us to go through all the existing wallet data and reprocess it and extend the databases. You can see our new schema in our documentation, but be aware you can't use it to get a working ElectrumSV wallet. We do not, and will never support this.

Removing complication

Previously we stored a whole lot of wallet data in memory, and every time we would process a transaction we would reconcile that transaction against the in memory data and then change the database. This was complicated, slow and hard to maintain. With the database enforcing consistency, we can completely get rid of these. This and more, have left the code with a lot less technical debt and made it much easier to develop.

Type annotations

We have added type annotations to a lot of the code, with the exception of the user interface and the unit tests. This provides us with a higher level of certainty that our code is correct, but the inherent flaws of bolt-on type annotations cannot give us as good a certainty as we would have if we were using a statically typed language. We will extend this support as far as we can, beyond this release.

Database writes

Our original database implementation had a workable custom approach to doing database writes, and waiting until they were complete. We now use the standard Python Future mechanism for this, which both makes the code more approachable to new developers and also allows us to write faster code. You can check out our implementation, if that's what you are into.

Transaction imports

When we receive a new transaction, we break it down and import it into the database. We store all the inputs and all the outputs, and we even store the offsets of the scripts in each of those. The goal is not to have to reprocess the transaction to get data from it, but to rather have that data easily accessible from the database. You can check out our implementation, if that's what you are into.

Useful information

Where can you learn more about how to use ElectrumSV?

We have a selected range of guides to common tasks that our users may want to do in our documentation, please check it out.

Where can you download ElectrumSV?

The only safe downloads are available from: electrumsv.io

Where can you get support or assistance?

Find our issue tracker here where you can create a ticket. Fill out the issue template, please! Otherwise we have no idea what steps you took or any of the other details and then we have to spend time asking you them anyway and you get help much later. Fill out the template for your own sake, if not ours!

We do not provide support over Twitter or any other forms of social media. Not only is it not guaranteed we will see your comments, it is a very painful way to do support that we avoid. If you need support, submit an issue on our issue tracker. Or you can raise subjects of interest on Unwriter’s Slack, or the Metanet.ICU Slack.

If you are a MacOS user and cannot install/run our latest release, please read this article.

What changed in the earlier versions?

Each of our release articles links to the article for the release before it. You can follow our releases back and see what changed in each, by the article that accompanied that release.

Read about what changed in ElectrumSV 1.3.13