If your cards seem to have disappeared, the most common cause is that Barcodes no longer has access to your iCloud account.
Barcodes stores and syncs your cards through iCloud. If iCloud access is turned off for Barcodes, or if your device is signed out of iCloud, your cards can disappear from the app until that access is restored.
In most cases, your cards are not gone permanently. Once iCloud is available again, they should reappear automatically.
Check iCloud access for Barcodes on your iPhone
- Open the
Settings app on your iPhone.
- Tap your name at the top.
- Tap
iCloud.
- Under
Saved to iCloud, tap See All.
- Confirm that Barcodes is listed and enabled.
If Barcodes was turned off here, turn it back on and wait a moment for iCloud to sync again.
Check that you are still signed in to iCloud
If you have signed out of iCloud on your iPhone, or if Apple is asking you to sign in again, Barcodes will not be able to access your synced cards.
- Open the
Settings app on your iPhone.
- Tap your name at the top.
- If you are asked to sign in, sign back in with the same iCloud account you used before.
- If you see any Apple Account warning or prompt to continue setup, complete it.
- Open Barcodes again and give it a little time to reconnect.
If you sign back in with the same iCloud account, your cards should usually reappear once iCloud finishes syncing.
Why this happens
This usually happens because:
- Barcodes was disabled in
Settings > your name > iCloud
- the device was signed out of iCloud
- Apple needs you to complete an account sign-in or verification step again
Still missing?
If iCloud is enabled for Barcodes, you are signed back in to the correct iCloud account, and the cards still do not come back after waiting a while, contact me through the support details in the app and I can help investigate further. 
