When Shopify's AI Section Generator Fails: A Step-by-Step Recovery Playbook

Marco builds and maintains Shopify themes for a handful of mid-market brands, mostly fashion and home goods in the $3M to $8M range. He sat down to spin up a new testimonial section the fast way, asked Sidekick to generate it, and got a flat refusal. “Unable to generate theme block at the moment.” He tried again. Same thing. Twenty minutes gone before he’d written a single line of Liquid.

He messaged us that afternoon, half annoyed and half curious. The promo videos make it look like one sentence and a section appears. His reality was a spinner and an error he couldn’t decode.

If you’ve hit the same wall, the good news is that the message is misleading. It reads like the AI is down. It almost never is.

What the error is actually telling you

“Unable to generate theme block at the moment” is a catch-all. It fires for several unrelated reasons and the wording gives you none of them, which is most of why it’s so maddening.

Underneath, the failures cluster into a few buckets. The theme you’re working in isn’t one the generator can safely write into. The section schema it needs to read or extend is malformed or non-standard. Your Sidekick session has gone stale and lost its authorization. Or Shopify’s generation service genuinely hiccupped, which does happen, just far less often than the error count would suggest.

The trap is reading “at the moment” as “try again later.” Sometimes that’s true. Mostly it isn’t, and retrying the same prompt against the same broken condition just burns your afternoon. So before you retry, it’s worth knowing which bucket you’re in.

One merchant put the frustration well when they told us the section generator “did not generate sections as shown in the promotional videos.” That gap between the demo and the desk is real, and it’s almost always one of the conditions below rather than a broken feature.

Theme compatibility: the silent prerequisite

The generator is pickier about themes than the marketing implies. It works cleanly on modern, Online Store 2.0 themes with a standard section and block structure. Push it at a heavily customized theme, a legacy vintage theme, or one where a previous developer rewired the section architecture, and it starts refusing.

This is the first thing to rule out, because it explains a huge share of the failures we see. If you’re on a theme that’s three major versions behind, or one that’s been hand-modified for years, the AI may simply not understand the structure well enough to write into it safely.

A fast test settles it. Duplicate a clean, current version of a stock theme like Dawn, switch to it in a development environment, and try the same generation there. If it works on Dawn and fails on your production theme, you’ve found your answer, and it isn’t the AI. Shopify’s theme architecture documentation is the reference for what “standard structure” actually means here.

That doesn’t mean you’re stuck on your real theme. It means the fix is about structure, not about waiting for the service to come back.

Check the section schema before you blame the AI

Every section carries a schema, the JSON block that defines its settings and the blocks it accepts. When you ask Sidekick to generate or extend a section, it reads that schema. A schema that’s malformed, has a trailing comma, or uses non-standard setting types will stop the whole thing cold.

Open the section file and look at the {% schema %} block with clear eyes. Validate the JSON in any linter. Watch for duplicate setting IDs, blocks that reference types that don’t exist, or a max block count that’s already maxed out. Any one of those can be the actual reason generation won’t proceed, even though the error blames “the moment.”

This step takes two minutes and it’s the one people skip. And it’s the one that most often turns up the culprit, a single broken character in a schema that’s otherwise fine.

If the schema is clean and the theme is modern and it still fails, then you move on to session state, which is where the genuinely boring fixes live.

Cache, re-auth, and the boring fixes that work

A surprising number of these failures are just a stale session. Sidekick holds an authorized connection to your store, and that connection goes sour more often than you’d expect, especially if you’ve had the admin open in a tab for hours or you’re bouncing between multiple stores.

The unglamorous sequence clears most of it. Hard refresh the admin. Log out of Shopify admin entirely and back in. Clear the browser cache for the Shopify domain, or just open the admin in a clean incognito window. Confirm you’re actually inside the store you think you are, because a multi-store account pointed at the wrong shop produces exactly this kind of silent refusal.

None of that is satisfying. But we’ve watched it resolve the “unable to generate” error more times than any clever fix, and it costs you five minutes against a problem that was about to cost you an afternoon.

If a clean session in a clean browser on a modern theme still won’t generate, now you have real evidence the service itself is the problem, and waiting an hour is finally the rational move rather than the lazy one.

When it generates but won’t render

There’s a second failure that’s sneakier than an outright refusal. The section generates, lands in your theme, and then renders as a blank space or throws a Liquid error on the storefront. Technically the AI did its job. Practically you’re still broken.

This usually traces to the generated Liquid referencing a setting or object that doesn’t exist in your theme’s context, or a block type the template doesn’t actually loop over. The generator wrote valid-looking code against assumptions that don’t hold in your specific theme.

The debug path is ordinary theme development from here. Preview the section in the theme editor, check the browser console and the Shopify theme inspector for Liquid errors, and read the generated code for references to settings or snippets your theme doesn’t have. Nine times in ten it’s a setting key mismatch or a loop over blocks that were never defined. Fixing it by hand is faster than re-prompting and hoping the next generation guesses your theme correctly.

The manual fallback that always works

At some point the calculus flips. If you’ve ruled out the theme, validated the schema, cleared the session, and it still won’t cooperate, stop fighting the generator and build the section yourself.

A basic custom section is not a big job. Create a new section file, write the Liquid markup, add a {% schema %} block with the settings you need, and reference it from the template or add it through the theme editor. For anything reusable, pull the markup into a snippet and render it. A developer who knows Liquid ships a clean testimonial or feature section in well under an hour, and it never depends on a service staying up or a theme being blessed by an AI. Shopify’s Sidekick and theme help covers where the generated sections are supposed to land if you want to compare.

That’s the quiet advantage of knowing the manual path. The AI becomes a time-saver you reach for when it works, not a dependency you’re stuck waiting on when it doesn’t.

A quick decision tree for next time

Here’s the order we actually run it, so you’re not guessing under pressure. Try the generation once. If it fails, test the same prompt on a clean Dawn theme to isolate theme compatibility. If Dawn works, your theme structure is the issue, so either generate there and port the section or build it by hand. If Dawn also fails, validate your section schema, then clear the session with a fresh incognito login. If a clean session on a clean theme still fails, it’s plausibly the service, so wait and retry once. And if you’ve burned more than thirty minutes total, just build the section manually, because by then it’s the faster road anyway.

The whole point is to stop retrying blind. Each step rules out one bucket, and you almost always find the real cause before you reach the bottom.

Questions we get every week

Is the error a sign that Sidekick is down? Rarely. Most of the time it’s your theme, a malformed section schema, or a stale session, and a genuine service outage is the least common cause despite the wording. Rule out the local conditions before you assume Shopify’s side is broken.

Why does it work on a new store but not my real one? A new store is almost always on a clean, modern theme, which is exactly what the generator wants. Your production theme is probably customized or older, and that structure is what’s tripping it up.

Do I have to use the AI to add a custom section at all? No. A developer can build a section and schema by hand in under an hour, and that path doesn’t depend on the generator working. Treat Sidekick as a shortcut, not the only road.

The section generated but shows nothing on the storefront. What now? That’s usually generated Liquid referencing a setting or block your theme doesn’t have. Check the theme inspector and console for Liquid errors and reconcile the code against your theme’s actual context.

What we keep telling clients

The single most useful reframe here is that an “unable to generate” message is a diagnostic prompt, not a verdict. The wording invites you to wait and retry, which is the one move that reliably wastes your time. Every minute you spend isolating the cause buys back ten you’d have lost re-prompting into the same wall.

We also tell teams not to build any real workflow on the assumption that the generator will always be there. It’s a genuine accelerator on a clean modern theme, and it’s a coin flip on a heavily customized one. The teams that stay calm about it are the ones who treat generation as one tool on the bench rather than the only way to get a section onto a page, so a refusal is an annoyance instead of a blocker. Knowing the manual path keeps you fast either way, because you’re never blocked waiting on a feature to behave.

Marco’s testimonial section, by the way, got built that same afternoon. We found his production theme had a customized section structure the generator couldn’t parse, so he spun the section up on a clean theme copy, ported the markup, and moved on. Fifteen minutes, once he stopped retrying the prompt and started ruling things out.

If your team keeps losing hours to theme tooling that won’t cooperate, we’re happy to take a look.