Where apps hide your files
Adobe Digital Editions saves the books you open in a Digital Editions folder inside Documents, while the .acsm file you download first stays in Downloads. Here is where each piece lives and what to do when loans expire or you change Macs.
Books you open in Adobe Digital Editions (ADE) are stored in a folder in Documents. On a Mac, an Adobe staff answer on Adobe's community forum gives it as:
~/Documents/Digital EditionsOn Windows the same folder is called My Digital Editions, which is why OverDrive's help page, written for both, calls it the "[My] Digital Editions" folder under Documents, and why some guides use the longer name. To see what yours is called, run this in Terminal (it lists names only):
ls ~/Documents | grep -i "digital editions"Or open it in Finder with Go > Go to Folder (⇧⌘G), typing ~/Documents/Digital Editions.
When you download a book from a library or a bookshop, you often get a small file ending in .acsm. It is not the book. OverDrive's help page explains that it is a file Adobe Digital Editions uses to download and open the book, and that it lands in your Downloads folder.
Opening the .acsm in ADE fetches the real .epub or .pdf and stores it in the Digital Editions folder in Documents. Adobe community threads disagree on whether ADE removes the .acsm afterwards, so you may find leftovers in Downloads. An .acsm that was never opened is a book you have not downloaded yet, and if the download did not complete, opening it again in ADE is the fix.
If a double-click opens the .acsm in a text editor instead of ADE, choose ADE as the app for .acsm files: select one in Finder, press ⌘I for Get Info, pick Adobe Digital Editions under Open with, and click Change All.
OverDrive says .acsm, .epub and .pdf files from a library expire, working only for a limited time after you download them. Expired files can stay on disk but will stop working; Adobe's FAQ says the error W_ADEPT_CORE_LOAN_NOT_ONRECORD means you are opening a loan that has expired or been returned.
To tidy up, use ADE itself rather than Finder. OverDrive's help describes right-clicking a book in ADE's library: Return Borrowed Item returns a loan early and deletes it from the Mac, and Remove from Library deletes the local copy only. Once a loan has ended, moving its leftover files to the Trash in Finder is fine too.
ADE ties protected books to your Adobe ID. Answers on Adobe's community forum put the authorisation data in a different place, in your Library:
~/Library/Application Support/Adobe/Digital EditionsThe file they name there is activation.dat. It is what makes this Mac an authorised device, and the posts describe moving it to the Trash as the way to force a fresh authorisation. A few users in those threads reported that the folder did not exist on their Mac, so do not be alarmed if yours is missing.
Do not copy that file to another Mac, post it in a forum or delete it to free space. If a book will not open, use ADE's own authorisation menu item (Adobe's FAQ calls it "Authorize this computer") with the same Adobe ID, rather than editing files. Adobe's FAQ also says an Adobe ID can be activated on up to six computers and devices.
The steps an Adobe staff member gives on the community forum, with the authorisation step added:
Adobe's FAQ draws the line clearly. Purchased books open on any device authorised with the same Adobe ID. A copied borrowed book will not open on another computer, whatever its authorisation, because the loan token is not copied with the file, so download current loans again from your library's site on the new Mac. Adobe community users also report ADE showing books as missing after changes to the folder, so keep a copy before you reorganise it.
The books folder is ordinary files in Documents, so Time Machine covers it. If iCloud Drive syncs Desktop & Documents Folders with Optimize Mac Storage on, files in Documents can be removed from the Mac to save space, and ADE can then report a book as missing. Download the folder again or keep storage free if that happens.
Do not rename or move books inside the folder while ADE is open; quit ADE first and expect to re-add them to its library afterwards.
The books themselves are ordinary files in Documents, so Finder can find them when the file name matches what you type, but a file name does not always match the title you remember, and the .acsm that started it sits in a different folder. The authorisation folder is inside ~/Library, which Finder and Spotlight leave out of ordinary searches.
Type .acsm into Everywhere to find every fulfilment file left in Downloads or elsewhere, or .epub to list the books ADE stored alongside any other EPUBs on the Mac. Add a word you remember from the title to narrow the list. Press ⌘↵ to reveal one in Finder. Documents and Downloads are protected folders, so these results appear once Everywhere has Full Disk Access. It matches file names only, not the text of a book.
In ~/Documents/Digital Editions. Windows calls the same folder My Digital Editions, which is why some guides, including OverDrive's, use that name.
In your Downloads folder, unless your browser saves elsewhere. An ACSM file is only a ticket that Adobe Digital Editions uses to download the real EPUB or PDF.
Library files expire after the loan period, so an expired EPUB or PDF stays on disk but will not open. Authorisation with your Adobe ID can also be missing; use ADE's own authorise option.
Purchased books, yes: copy the Digital Editions folder and authorise ADE on the new Mac with the same Adobe ID. Adobe says a copied library loan will not open on another computer, so download current loans again there.
Everywhere keeps track of every file on your Mac — including the folders Spotlight hides and drives you have unplugged. Free for a day, then $19 once.
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