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Why is Dropbox re-indexing my Dropbox folder (which is on an external drive) when I reboot my Mac?

JeannettePeter

Synchronization Problem
We work as a team using Dropbox and store our data on an external drive. Everything had been working fine until now. Now my Mac is constantly indexing / syncing. It’s a new device, a new external hard drive, and I have a stable and fast internet connection. The external hard drive is formatted as required by Dropbox. The storage location is /Volumes/T9-Dropbox/.CloudStorage/Data/Dropbox-name. Today, shortly after I restarted my Mac, Dropbox re-indexed my approximately 2.2 TB of data. This took about 6 hours. After that, it started syncing, which again took a very long time. Unfortunately, my Mac crashed before the synchronization was complete, and I had to restart it. Now it’s starting the reindexing process all over again. Why is this happening? This has never happened in all these years. Why is the Mac reindexing even though nothing in the data changed over the weekend? How can I solve the problem? The datas are on my external drive, but I can't work with them until it's synchronized. I'ts an Apple M5 Pro, MacBook, macOS Tahoe 26.5.1

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Jay

Hi @JeannettePeter, thanks for bringing this to our attention.

If there is a Dropbox desktop application update, the app might require a re-indexing of the files to be certain that there were no changes during the update process. What version of the app are you running on your machine?

How many files do you have in your Dropbox folder approximately? Are the files all marked as available offline, or do you have some online-only, or are you using selective sync?

Any details you can provide would help me greatly!

JeannettePeter

Hi Jay. When I check my Dropbox app in Finder, I see version 260.4.2926. There's a lot of data. There's about 2.12 TB on my external hard drive. When I check the folders in my Dropbox app (Settings / Syncronizing / “Selective Sync” / choose folder), I have about 2.96 TB. I can’t see exactly how many files there are—I’d guess about 250,000—but I’ll know once the system starts syncing. Indexing is only at 63% right now—it’ll take a few more hours. In my settings, I have ticked available offline. All datas must be available offline.

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Jay

Thanks for the info. With that large amount of data and files, it would take time for the app to finish indexing fully.

When you reboot your device, is the external drive already connected to the machine, or do you connect it after logging in?

JeannettePeter

When I reboot, the external drive is already connected to the machine. Just for your information: I have rebooted about 6 hours ago (by accident) and it re-startet again with indexing. I wait now before I do anything until it is synchronized. The indexing is at about 97% right now. Then it will start synchronizing that will take another 4–6 hours at least. So I wait and reply then.

Jay

Thanks for the update, keep me posted with any changes in the syncing process, or if it repeats again when you reboot the machine.

JeannettePeter

Sorry for the late reply. The data is here again. I had a lot of conflicting files to sort out. Today, Dropbox was running smoothly. However, I still have a question: when does Dropbox re-index and re-synchronise? It took about nine hours, even though the data was already on my external drive. I can't afford to stay offline another whole day. What could be the reason Dropbox is reindexing? I appreciate any feedback.

Jay

The Dropbox desktop application could re-index files if there are any changes to the desktop app itself (such as an update), and might need to do so on some occasions to ensure that it has the latest version of the files, or if certain apps or services scan or access multiple files in the folder.

There isn't a specific way to determine when the app would need to re-index the files in the Dropbox folder.

Megan

Hey there, @JeannettePeter!

Following up to confirm whether your issue is resolved or if further support is needed. We're here to help either way.