There's a moment every spreadsheet user knows: you have the data, you can see the shape it should take, but the formula that seems obvious just won't cooperate. That's exactly where this question lands. The user has a column of comma-separated values and wants to split each cell into its own row of a dynamic array. The instinct to reach for `BYROW` with `TEXTSPLIT` inside is a good one, it's logical, it's clean, and it should work. But it doesn't, and the reason is worth understanding if you're serious about building formulas that scale.
Here's what's actually happening. `BYROW` passes each row of the array into the `LAMBDA` as a single value, but when you call `TEXTSPLIT` on that value, the result is a 1x4 array. `BYROW` expects each iteration to return a single value, one per row, not a spill of multiple columns. So instead of producing a 6x4 array, it errors out because the function can't reconcile the fact that you're asking it to return more than one column per row. This is a classic mismatch between the function's design and the shape of the output you're after. The formula isn't wrong in spirit; it's just using a tool that's built for a different job.
The practical takeaway here is that you need a different approach, and the solution is more elegant than you might think. Instead of forcing `BYROW` to handle the split, you can use `TEXTJOIN` to collapse the entire column into a single string of comma-separated values, then run `TEXTSPLIT` once across that entire combined string. The result is a single dynamic array that spills into the rows and columns you need. For example, `=TEXTSPLIT(TEXTJOIN(",", TRUE, A1:A6), ",")` would give you a 1x24 array, but if you want it to match the original row structure, 6 rows, 4 columns, you'd need to adjust the delimiter or use a different approach, like `WRAPROWS` to reshape the output. The key point is that the fix isn't about making `BYROW` work; it's about rethinking the problem as a single transformation rather than a row-by-row operation.
What this teaches us is that modern array formulas reward a shift in perspective. The old way of thinking, one formula per cell, dragged down, doesn't apply when you're working with dynamic arrays. You're no longer writing instructions for a single cell; you're defining the shape of an entire result. That's a powerful mental model, but it requires you to stop thinking in terms of loops and start thinking in terms of whole-data transformations. The user who asked this question is on the right track, they're exploring, they're experimenting, and they've hit a wall that's more about tool selection than capability. The answer isn't just a formula; it's a better understanding of how the functions in your toolkit actually behave. And that's the kind of insight that turns a frustrating error into a permanent upgrade in how you work.