This is a textbook case of the problem living in the user's environment, not in the file itself. When a 30MB Google Sheet with pivot tables and complex formulas downloads and opens on other machines but refuses to open on a primary workstation, the file is not the culprit. The error message is a symptom, and chasing the file while ignoring the local configuration is a mistake we see far too often in spreadsheet workflows.
The user has already done the right thing by testing browsers, clearing cache, and attempting Excel's "Open and Repair." Those are logical steps, but they miss the real issue: Excel on that machine is likely hitting a resource limit or a temporary folder conflict that has nothing to do with the data itself. The fact that an older version of the same file opens fine is the clue. Something changed locally, not in the spreadsheet. It could be a Windows temp directory that has grown unwieldy, a stale Excel add-in that's intercepting the file on load, or a memory allocation threshold that the newer, more complex file trips over.
What this means for anyone dealing with similar frustrations is straightforward: stop treating the file as the enemy. Start by looking at the local Excel installation and the Windows environment. Clear the temporary files with a clean disk cleanup, disable unnecessary add-ins, and check whether the machine has enough free RAM to handle a 30MB file with pivot tables. The user's suspicion about a "temporary folder conflict" is not far-fetched. Excel writes to the temp directory during file validation, and if that directory is corrupted or full, the file will be flagged as corrupt even when it is perfectly fine elsewhere.
The practical takeaway is this: when a file opens on other computers, your data is safe. Your next move is not to re-download the file again, but to clean house locally. Run a disk cleanup, move the temp folder to a different drive, and test Excel with add-ins disabled. If that fails, check the Windows event viewer for application errors tied to Excel. The solution is almost certainly on the machine, not in the spreadsheet. And that is good news, because it means the work you put into those formulas and pivots is not lost. It just needs a less cluttered path to open.