Why your team keeps overwriting the shared spreadsheet

Every claim below is quoted from Microsoft’s own documentation · checked 21 August 2026

Search this and you get forum threads from 2016 telling you to switch on a feature Microsoft has since hidden. The advice keeps missing because three completely different things all get called “sharing a spreadsheet”, and they fail in three different ways. Here is which one you are actually in.

1. A file on a network drive: Excel was never going to let two people in

An .xlsx sitting on a shared drive or an old file server is a single file with a single lock. The second person to open it gets read-only, or an offer to be told when it is free. Nobody is overwriting anybody yet — what usually happens next is that someone takes a copy just to get on with the day, and the overwrite arrives later, when the copies are reconciled by hand. If your team emails versions around, this is the case you are in, and no Excel setting fixes it, because the problem is that there are now several files.

2. The “Share Workbook” button you are hunting for is hidden on purpose

Most of the older advice tells you to switch on Shared Workbooks. Microsoft calls it “an older feature”, says that “the Share Workbook button has been hidden”, and states that it “has been replaced by co-authoring”. You can still dig it out of the ribbon settings, and people do — which is the trap, because it works just well enough to keep. Microsoft’s own page lists what you give up: in a shared workbook you cannot create or insert tables, change conditional formatting, delete worksheets, create charts or PivotTables, use macros, or use threaded comments, and it cannot be edited in Excel for the web at all.

So the classic sequence runs: someone switches it on to stop the overwriting, someone else later cannot insert a table and never finds out why, and the workbook quietly becomes the file nobody is allowed to improve.

3. Co-authoring works — until one person opens it in the wrong Excel

Co-authoring is the modern answer and it genuinely works, but Microsoft’s requirements are stricter than most teams realise:

• The workbook must live on OneDrive, OneDrive for Business, or a SharePoint Online library. A network drive is not one of those. Neither is your own server: Microsoft states that “SharePoint On-Premises sites (sites that are not hosted by Microsoft) do not support co-authoring”.
• The file must be .xlsx, .xlsm or .xlsb — and co-authoring “does not support the Strict Open XML Spreadsheet format”, which is a Save As option people pick without thinking about it.
• Everyone needs a version of Excel that supports it.

That last point explains the symptom that otherwise makes no sense — it worked yesterday, and today the whole team is locked out. Microsoft: “The most common one is because someone has opened the file with a version of Excel that doesn’t support co-authoring. If just one person does this, then everyone else will get the ‘locked’ error.”

One straggler on an old build locks everybody, and nothing on screen tells you who it was.

The order that actually fixes it

1. Move the file to OneDrive or SharePoint Online. Not a mapped network drive, and not an on-premises SharePoint — by Microsoft’s own statement, that one cannot co-author at all.
2. Save it as .xlsx, .xlsm or .xlsb, and not as Strict Open XML.
3. Find the straggler. A single unsupported Excel is enough to lock everyone, so check this before you change anything else.
4. Use version history to recover what was already lost. OneDrive and SharePoint Online keep previous versions of the file, and that is the genuinely recoverable part of this problem.
5. Stop the copies. Every emailed duplicate re-creates the original problem, and it is the one step no software does for you.

When it stops being a spreadsheet problem

Everything above assumes several people are editing one document. Often that is not what is happening. The tell is simple: if two people are almost never in the same cell, and what they are each doing is maintaining their own rows — their clients, their jobs, their stock — then nobody wanted a shared document. They wanted a shared set of records, and a document is the wrong shape for that.

The difference is worth naming, because it is why the overwriting keeps coming back after each fix. A cell has no owner, no type and no history. A record has all three. Priya editing her own job is not a conflict with Tom editing his — but inside one file it is, forever, no matter where you store the file.

What happens when two people do edit the same record

Different rows never colliding is the easy half. The question a page about overwriting ought to answer is the other one, so here it is plainly.

Every edit records what it was based on. If you changed the delivery date while a colleague changed the phone number on the same record, both land and neither of you hears about it: the two changes touch different fields, so they merge. If you both changed the delivery date, to different dates, nothing is chosen for you. Both versions are kept, the record is marked as conflicted, and a person decides which one is right.

That is a deliberate choice and it is worth understanding, because most tools do the opposite. The common approach is that the last save wins: your colleague’s date replaces yours, silently, and the only trace is that the number is now wrong. On a shared file it is worse again, because the whole document is replaced rather than the field. We would rather interrupt one person for ten seconds than put a wrong figure into your records where nobody is looking for it.

Nothing is discarded to make that work. Each version is stored permanently as its own revision, so both readings survive in the record’s history whichever one is picked.

The cost of that choice, stated: it asks a human, which is slower than a tool that simply picks one. And it is not live co-editing — two people typing into the same paragraph at the same time is a document-shaped problem and we do not solve it. If that is what you need, you want a document, not us.

Why we wrote this

We build Bionic Forms and we would like teams who have outgrown a shared spreadsheet to consider it, so this is not neutral. What we can offer instead of neutrality is that every limitation above is Microsoft’s own documentation rather than our characterisation, and that we will say plainly where we help and where we do not.

Where we help: the same information, but as records. Two people editing different rows never collide. Every record keeps its own history, so “who changed this, and to what” is a question with an answer. Permissions are per person rather than per file, and people outside your team can fill in a form without an account at all — which is usually why the spreadsheet was being emailed around in the first place.

Where we do not: if what you have really is a model — formulas, scenarios, a financial sheet several people reason about together — then you want a spreadsheet, you want co-authoring, and the list above is your fix. We do not run spreadsheet formulas, and we would rather say that here than after you moved. We do now read an .xlsx directly — drop the workbook and we take the sheet — but only when it holds ONE sheet of data. A workbook with several is refused, naming the sheets it found so you can choose one and Save As CSV; we would rather ask than guess which sheet you meant. A shared Google Sheet link still works too.

Sourcing, plainly: every quotation comes from Microsoft’s own Office support documentation — collaborate on Excel workbooks at the same time with co-authoring and about the shared workbook feature — checked on 21 August 2026. Where we describe what happens on a plain network share, we are describing ordinary file locking rather than quoting a document, and we say so rather than dressing it up as a citation.

Being straight about where we are: Bionic Forms is pre-launch. There is no iOS or Android app; the macOS, Windows and Linux desktop builds and the web app are what exist today, and the Windows build is not code-signed yet, so Windows warns the first time you run it, and we have no external customers to point at.