Formie submissions kept submitting 150+ times

[akiraWalk]

Describe the bug

Hi Formie team, Over the xmas break a customer made a form submission and it triggered a series of unfortunate events where they received the submission email 150+ times. this stopped when it was manually forced so in the queue manager. The client has since turned off the form notification. Looking at the logs we suspect it may have something to do with emojis.

Steps to reproduce

1. make form submission on /community-consultation-draft-prospect-vale-blackstone-heights-structure-plan
2. Use an emoji
3. submit

Form settings

• Multi-page form: No
• Submission Method: Page Reload
• Client-side Validation: Yes
• Custom Form Templates: No

Craft CMS version

5.8.21

Plugin version

3.1.6

Multi-site?

No

Additional context

Will need a support email to provide sensitive logs/db/composer file

[engram-design]

I've seen this happen only once, and on a Craft 4 install where Sent Notifications were sent into a loop, mostly due to the lack of emoji support in Craft 4. But that should be less of an issue on Craft 5.

One thing to check first is your database table encoding/charset, particularly for the formie_* tables. By default, I think they should be utf8mb4 / utf8mb4_0900_ai_ci. Running the php craft db/convert-charset command to ensure things are converted correctly is a good first thing to try.