How to restore an old version of a Trello card?

Time needed: 20 minutes

How to restore previous contents of your card in Trello?

1. Get the ID of your card

   First, we’ll need the id of your card. You might know this already, but you can grab it from the URL after the part that says /c/. In my sample below, card id is H65WGtkZ.
   
   

2. Navigate to https://trello.com/1/cards/[id] to see your card

   Now you can call the API with the id of the card. You can do this in the browser since you already have an active session – navigate to https://trello.com/1/cards/[id]/actions?filter=updateCard:desc to get your card’s latest changes.
   
   This way, you’ll get the latest changes (type=”updateCard”) to your card in a descending order. Nifty!
   

3. Find the part that says “old”

   Now we’ll need to get the old values. For me, the latest change was the one that overwrote the actual contents (shown as “asdf” overwriting the good “old” stuff in the sample below), but of course if you need to go further in the history, it might take a bit of browsing for you.
   
   It’s helpful to use some way to prettify the JSON, I’m using a browser extension (right after berating them in principle, yes) but you could just as well copy-paste the contents into Notepad++ (where you can use, of course, a plug-in to format them nicely).
   
   Anyway – under “old” you’ll find the old values for your different fields. In my case, just “desc” changed, and it changed quite dramatically.
   
   

4. Copy-paste the field to VS Code

   Now we’ll want to fix the formatting. You can’t just copy-paste the contents into Trello, because that’d be too simple. You’ll need to replace at least the line breaks.
   
   You can probably do this somewhere online, too, but I chose to use VS Code for this because why wouldn’t I. Copy-paste the contents into a new VS Code file.

5. Replace newline escape sequences with actual new lines

   Now you can hit ctrl+H (or alternatively action button + shift + command-alternator + kverg-tab + H if you’re on Mac) to bring up the search & replace dialog.
   
   Search for “\n” (newline escape sequence), and in the replace-textbox just hit shift+enter. This’ll let you replace all characters for the newlines (\n) with what’s actually interpreted as a new line.
   
   Sounds convoluted but try copy-pasting the content with the escape sequences not replaced or properly interpreted into Trello, and you’ll first get a code-block, and if you choose to paste without formatting, you’ll just get a wall of text without any line-breaks (or any other formatting – even markdown!)
   
   

6. Copy-paste the replaced text into Trello

   Now you’re finally ready to copy-paste the text back into Trello! You’ll still want to do this without formatting by pasting with ctrl+shift+v (or, again, action pad right click + escape combulator + shifteral + v on Mac), and Trello should interpret your content as markdown again.