Snapshots fail with a cryptic "…is not defined" error

Every snapshot fails with a short, cryptic error — _0x5971 is not defined, _0x2ba7 is not defined, or something else in that shape — while everything else (reading layouts, moving objects, editing text) keeps working normally. Nothing on your side caused it, and your documents are unaffected.

The cure is the same whichever code you see: get onto the current version of Sidekick. How you do that depends on which of two situations you’re in. Ask your AI assistant to run sidekick health and look at the server version it reports.

If the version is 1.0.29

This was a fault in version 1.0.29 itself, fixed in 1.0.30. The part of Sidekick this affects keeps itself up to date automatically, so there’s nothing to reinstall — you just need it to pick up the newer version:

1. Quit your AI assistant fully — on Windows, closing the window leaves it running in the system tray, so right-click the tray icon near the clock and choose Quit; on a Mac, press Cmd-Q.
2. Reopen it, open InDesign, and try a snapshot.

Run sidekick health again and you should see 1.0.30 or newer.

If the error looks completely unchanged after restarting, the most likely reason is that an older copy of Sidekick is still running in the background and is still the one doing the work. That’s what fully quitting (step 1) is meant to clear — so if you closed a window rather than quitting from the system tray, or another AI assistant is still open, close everything down completely and start fresh.

If the version is 1.0.15 to 1.0.18

A batch of versions from early July 2026 could get stuck running an older backup copy of Sidekick that was built into the extension at the time. That backup copy has a broken snapshot feature and — the frustrating part — it can’t update itself, so the problem never clears on its own. This almost always happened on Windows.

The telltale is a sidekick health that shows the server stuck on 1.0.15–1.0.18 even though the update status claims everything is current. The fix is a one-time fresh install of the extension:

1. Download the latest version from the install page.
2. Double-click the downloaded file so Claude Desktop offers to install it. If double-clicking doesn’t open Claude Desktop (common on Windows), open Claude Desktop and use Settings → Extensions → Advanced Settings → Install Extension to pick the file instead.
3. Quit Claude Desktop fully — on Windows, from the system tray icon near the clock; on a Mac, press Cmd-Q.
4. Reopen Claude Desktop, open InDesign, and try a snapshot.

Once you’re on a current version, updates arrive automatically again — you won’t need to do this twice.

One thing that sounds similar but isn’t

From version 1.0.29, every install carries a spare copy of Sidekick — on purpose, and a working one. If your health check mentions that Sidekick is serving the copy that shipped with your install, that is the healthy fallback doing its job, not this error returning. What that message means explains it.

If snapshots still fail after all this, contact support with the sidekick health output and whether you’re on Windows or Mac, and we’ll dig in with you.