Why is Quicken still so buggy?

I'll bite. I think the answer to your question is one word: synchronization. Synchronization is HARD. VERY HARD.

Back in the day when Quicken was solely a desktop app, everything was self-contained. Quicken completely controlled all aspects of the software. They owned the UI that captured the user data. In that programming model, it is relatively easy to ensure data integrity because you completely control all aspects of the workflow.

Jump ahead to the modern connected world. Now Quicken handles multiple sources of data input, from 1000s of financial institutions, using several (WC, EWC, EWC+, DC) connection methods. The workflow to get data into Quicken is now much more complicated, and, even more importantly, largely out of Quicken's direct control. Where the data acquisition process used to be a user typing into a UI controlled by Quicken, it is now a whole series of steps and conversions across many different layers in a pipeline, each of which is a potential cause of data corruption or failure. Furthermore, Quicken doesn't control many of these moving pieces, it is just on the receiving end. Just look at this Community Forum, which groups have the largest number of questions? Download, Add/Update Accounts (Windows) followed by Errors and Troubleshooting (Windows).

Another aspect of synchronization, over which Quicken does have more complete control, is their own web UI and mobile apps. But these still present challenges, merge conflicts and upgrade safety, to name just two. A merge conflict can occur when the "same" data resides in, and can be edited from, multiple places. The Quicken desktop file is the source of truth, and the web UI and mobile apps are companions, but they allow edits to the data. These edits may conflict in irreconcilable ways, resulting in a merge conflict when the data is ultimately synced back to the single source of truth, the desktop app. Some of these conflicts may be easy to resolve, but others are not. For example, you may have a single transaction on desktop that you split in different ways on the web UI and mobile. When you synchronize, these disparate versions cannot be simply merged. How does git, the most popular version control system used by developers, handle these types of situations? It doesn't! It throws up its hands and makes the developer resolve the conflict. Of course, a consumer app like Quicken can't do that. Instead, it has to have some heuristics to guess what is the best course of action, which adds complexity.

Yet another aspect of synchronization is upgrade safety. Say, Quicken decides to add a new Roth 401(k) option to the after-tax deductions of the paycheck wizard, which they recently did. When they QA this change, there are many use cases that need to be considered. Does it work when a new paycheck is created? Does it work when a user with a paycheck created 20 years ago tries to edit their paycheck? Does it work when this option is added to the paycheck in the desktop app, and the user then syncs a change they made in the old paycheck from mobile? This should be QAed using both the old version of mobile app that doesn't know about the new Roth 401(k) option and the new version that does. Wait, there isn't just one mobile app, there are two, one for iOS, and another for Android. Need to test both. Wait, there is also the web UI. Need to test that too. This one seemingly simple addition has expanded into a complex tree of uses cases that all need to verified. It is very easy to overlook some of these more obscure corner cases, potentially leading to bugs in the app functionality, or worse yet, corruptions in the data file.

With all of those challenges, I would guess that synchronization is a necessary "evil" from a business perspective. How many users would buy Quicken if they had to enter all of their data manually? (One, probably only me.) Personally, aside from two financial institutions that offer Direct Connect, I enter all of my transactions manually: checking, credit cards, loans, mortgages, bills, investments, etc. For me, it's just not that hard. In fact, I'd even argue that it's less time consuming than downloading and having to deal with the inevitable corruptions that will occur.

I've been using the same data file for over 25 years, really without incident. Years ago, I once tried using the bill download feature. It was a disaster, causing an uncoverable data file corruption. I reverted to a backup and resumed manual entry.

To me, the real benefit of Quicken is not the automation, but the holistic analysis it offers. I can get a report showing me (properly categorized) annual spending for the last ten (or more years), an accurate IRR investment performance report for any time period (account, security, etc), an accurate tax estimate, a decent retirement funding estimate, and a whole lot more. All of these depend on the continuity, reliability, and accuracy of the underlying data, which I ensure by manual entry.

Quicken is my favorite app. While it's good at what it does, it could be even better. With the wealth of data it holds, there's an opportunity to offer so much more insight and functionality. However, I fear it may never live up to that potential because a disproportionate share of development resources is spent playing whack-a-mole with all the recurring synchronization issues. I see no easy solution to that, and I understand that for most people, automation is probably their P1. But, if only some of those resources could be freed up, there is great opportunity to build an even more differentiated product.