@tim820 I appreciate your input. i thought the exact same thing about this, very tedious and not amenable to batch handling. --> "Finally, the WSU process uses the Linked Attachment Base Directory setting in a somewhat uncommon way - combined with using right-click Add Attachment for every single PDF file you download (!)."

This is particularly discouraging for my case, because my zotero library is now over 1000 docs, thus highly intractable to switch all of them to linked via individual right-click.

A quick check of the database integrity within the advanced preferences shows there are currently no errors. And based on your distinction above, it sounds like changing the Linked Attachment Base Directory to the Dropbox folder rather than the Data Directory Location is the least risky move.

To offer more information -- the pdf emblem on my mobile computer's zotero instance is grayed out (the problem im trying to solve) even though both instances use the "...username\Dropbox\Papers" dir as the Linked Attachment Base Directory

when i try to open one of these pdfs, it shows that zotero is still looking in its default location: "The attached file could not be found at the following path: user\Zotero\storage\PHFWPI9E\Tang et al. - 2023 - Expectation violations enhance neuronal encoding.pdf It may have been moved or deleted outside of Zotero, or, if the file was added on another computer, it may not yet have been synced to or from zotero.org."

So what do you intuit is the best solution here to allow my pdfs openable across both computers? Does this imply that i need to just copy my entire "user\Zotero\storage" dir from my desktop over to my mobile computer, and periodically overwrite it across both machines like this until the end of time? There has to be a better way that doesnt involve redundantly storing pdfs on both computers and manually updating them...

@connor_gray your Zotero *data* is safe and risk-free ... as long you did *not* set the Data Directory Location to Dropbox (the WSU instructions you used are not 100% clear enough to be sure that most people will avoid that). And of course if you have it backed up well.
https://www.zotero.org/support/zotero_data#backing_up_your_zotero_data

Also, to be clear, online syncing of all that *data* is free. The online storage quota limit only applies to file attachments you sync online on Zotero servers (*file* syncing).

So the question is where are your PDFs now, how to get them (now and in the future) to Dropbox, and have them accessible across computers ? The example you gave for PHFWPI9E shows that that particular PDF is in *local* Zotero storage, ie it is not a linked file (in Dropbox). The PDF icon for that particular file in the main window will likely not show a chain-link overlay that signifies a linked file.

The solution that most people (and there are many, many of them) use for linked file setups is the Zotfile plugin (not the way WSU describes). As pointed out above, Zotfile is not available in Zotero v7 (currently still in beta, so most people should still be in Zotero v6). Several plugins will likely provide the same functionality in v7 for those people (but that is still evolving). In any case, it is always possible to switch back to local Zotero storage of PDFs if you want to; for example if you can afford paid Zotero storage in the future, or if you want to use features that linked files don't work for - the mobile app or Groups. If your PDF needs are over 300mb and you want to use those features, your only real option is paid storage.

Zotfile handles automatic storage of your PDFs to the Custom Location specified in Zotfile Preferences (eg Dropbox) as *linked* files. Their exact location is stored in the Zotero database, so it knows where to find them.

The WSU instructions you used provide no means to automatically manage the storing process - they require you to manually (right-click) attach each PDF you download. That happens automatically with Zotfile. For example when the Zotero web connector downloads a PDF from a journal web site you have access rights for, Zotfile automatically sends it to the Custom Location as a linked PDF.

For that Zotfile setup, you would have Zotero (free) data syncing turned on, and Zotero (quota-limited) file syncing turned off, in Zotero preferences. As long as data syncing is turned on with any Zotero setup (Zotfile or no Zotfile), you would never have to do what you described in your last para - your data would always be synced (for free) across computers.

When you have set up Zotero on another computer to use the same (free) account, all your *data* will sync to that computer, as will future data changes (both ways). But you are responsible for setting things up so that the *linked PDFs* are in the Zotfile Custom Location on that computer, and synced (eg by Dropbox). If the Custom Locations are different on the two computers, set Zotero's Linked Attachment Base Directory, so it then knows where to look for them.

I don't disagree that paid local storage works very well for many people who can afford it. ;) I just think that many other people need to use the available alternatives like linked files - academics in places where the online Zotero storage cost is problematic, retired people, students, etc. WebDAV is another option, which seemingly gets more official support from devs than linked files. Although if posts here are any indication, it runs into problems more often than Zotfile setups do.

My only real concerns with a Zotfile-based approach include the mentioned remaining uncertainty around which of the current new plugin candidates will best provide that functionality in the future in Zotero 7 (along with Zutilo, there would seem to be too many people that rely on those plugins for solutions not to happen before Zotero 7). And also that the Zotfile documentation is out of date (still referring to annotation extraction). Although all the important bits are still as described IIRC. Hopefully in the future instead of long posts like the above we can just go back to 'read the plugin instructions'. Finally there is the clearly stated inability of linked files to work with Groups, nor iOS (other than with a less efficient external PDF viewer workaround; or Zotfile's send-to-tablet, that looks unlikely to remain an option in v7).