What could possibly go wrong?

Fifteen minutes before doors, the check-in area looked calm.

No desks, just four roped-off columns guiding people in.
Pre-printed QR lanyards hung on racks, colour-coordinated by registration type so staff could grab the right one quickly.
Delegates had their personal QR code in the event app (iOS/Android) or the PWA in their browser.
The team used the admin view to scan that personal QR and assign a lanyard QR from the rack. No names printed; identity lived in the mapping. Later, exhibitors would scan the lanyard to capture leads against the right person.

Clean loop. Fast queue.

Then the app hesitated. A spinner here. A frozen screen there.
Mutterings came from the queue as they tried to access the app from their phones.

There was a Plan B, a standalone check-in system, but with check-in already open and four columns moving, swapping systems mid-flow is like changing tyres while still rolling: possible, not graceful.

So the delegate team used their experience.
They opened the offline attendee list synced an hour earlier and kept people moving by name and company while two colleagues worked on recovery. Venue Wi-Fi wobbled; hotspots stepped in. Front-of-house used one calm line:

“We’re checking in manually for a few minutes, thanks for your patience. We’ll get you in as quick as we can.”

About ten minutes later (and thanks to the on-call tech support team), the app recovered.
Assignments continued: personal QR → lanyard QR.
The room filled. From the outside, it looked smooth.

From the inside, the lesson was clear:

Plan B isn’t a different system. Plan B is the same journey, by another road.

With no printers on site, lanyard QRs pre-printed and colour-coded, and four roped columns instead of desks, the critical link was the mapping between personal app QR and lanyard QR. If the back-up can’t preserve that mapping in the moment, data breaks and lead capture suffers.

Here’s how smart teams now design for that reality.

What to copy if you run events

1) Hot-swap, not hard switch
Back-up should live inside the same check-in flow: in this case, scan personal QR → assign lanyard QR → log the mapping. If the event app/PWA wobbles, an offline mode uses cached data on the very same screens. No re-routing the four columns. No new instructions.

2) Cache the right data
Before doors, admin devices cache:

• attendee list and personal QRs,

• lanyard QR ranges by registration type,

• existing assignments.
  If connectivity drops, offline check-in continues and syncs later.

3) Protect the mapping
With no names on lanyards, the mapping is everything. Treat “person QR ↔ lanyard QR” as sacred. Even if you pause to check people in by name for a few minutes, allocate the correct lanyard QR and record it for reconciliation.

4) Flip criteria + a drill
Agree the line: “If X% of scans fail for Y minutes, flip to offline.” Practise the swap the day before. Pull Wi-Fi. Pause the app. Keep the queue moving across all four columns.

5) Roles beat heroics
Who calls the flip? Who controls the four columns? Who talks to the organiser? Who liaises with the platform team? Say it out loud in the briefing. Twice. Print the FOH script.

6) ‘Essentials’ page for delegates
When the attendee app misbehaves, a lightweight web page with agenda, room map, Wi-Fi code, help number and a fallback QR keeps things calm. Put the URL and a QR on signage near the ropes.

7) Incident log
Start a timer, note what failed, what was tried, what worked, and what will change. That’s how you remove luck from the next event.

Edge cases worth assuming

• App/PWA stalls (delegate or admin): admin continues on cached data; delegates present a fallback QR from the Essentials page; QR-to-QR assignments continue.

• Venue Wi-Fi sulks: hotspots take over; if both links die, offline mode continues and syncs later.

• No printers on site: still fine, lanyards are pre-printed and colour-coded; maintain the mapping and reconcile afterwards.

• Attendee not on list: quick-add on a cached form; allocate a lanyard QR; dedupe later.

• VIPs: pre-pulled, clearly labelled lanyards by colour/type.

• Unexpected evacuation: grab-sheet headcount by alphabet band; reconcile afterwards.

The point

Event check-in should look calm, even when the tech has a moment.
That doesn’t happen by luck. It happens when Plan B keeps the same journey alive, scan, assign, log, online or offline, printers or not, desks or roped columns.

Make the plan. Pack the kit. Practise the swap.
Queues move. Stakeholders relax. Lead capture survives.

Copy-paste checklist for organisers

• Admin devices cache attendee list, personal QRs and lanyard QR ranges at T-60

• Back-up uses the same scan → assign → log journey

• Two networks tested on site (venue + at least one hotspot)

• FOH one-liner printed and rehearsed (visible near the ropes)

• Essentials page live (agenda/map/Wi-Fi/fallback QR) and signage updated

• Flip criteria agreed (X% failures for Y minutes) + ten-minute drill done

• Incident log template open; fixes assigned post-event