It can be a little tricky to get the file imported because you’ll need to make sure Quicken associates it with the correct account. You may need to change the name of the bank on your account before you import the file. The easiest way is to create a new account when you import the file as shown in the image. You can then go in and edit the name of the account, but you’ll need to leave the name of the bank set to Washington Mutual.

I think it is stupid that you have to do a work around like this to do something as simple as importing a file of text data, but evidentally it is part of Intuit business model. It should be fairly easy to write an automator script or use folder actions to automatically replace the necessary lines. If you are interested in seeing a future article about how to setup automatic conversion, leave a note in the comments. (update: automated method article)

Another possible way to work around the limitation is to redirect all traffic to Intuit to your local machine and return the proper codes to authorize the transaction regardless of which bank a QFX file comes from. Ideally someone could setup their own server to act like Intuit’s server and return affirmitive responses to all requests.

Quicken For Mac 2017 Error 29 Account Mismatch Password

Update: more information in a new article