Issue Summary

If a user adds multiple attachments to a card simultaneously (such as 193 JPEGs, each between 39kb and 708kb), Trello will stop the upload and give you an error in the console at some point:

500 - Internal Server Error

We thought it was related to this JAC, but it was fixed. However, one of the customers still faces errors.

Steps to Reproduce

1. I wasn't able to reproduce. But the customer uploads around 193 JPEGs at once, each between 39kb and 708kb
2. Wait, and you'll see an error. There is a HAR in the original ticket mentioned in the comments, the one this bug report originated from.

Expected Results

Trello would upload without a problem, or prevent the user from adding that many files at once, to prevent the error.

Actual Results

An error and the message in the console. The majority of files aren't attached.

Workaround

Upload fewer files at once.