My daughter is running into the same issue that I had when my TD E-series orders were rejected. This was due to my investment risk profile. Unfortunately, she has set up a TFSA with TD Mutual Funds (not TD Direct investing). As we learned to use TD E-series funds in a TD Mutual Fund account, you must complete many steps. None of these steps include the change your investment risk profile to stop having your TD E-series orders rejected.
I have talked about using the E-series funds to set up a simple Couch Potato investment portfolio. My daughter is going to use the idea for her TFSA account.
The application to allow you to use TD E-series Index Funds in your TD Mutual Fund account is straightforward and easy to fill in. You must do this if you end up with a TD Mutual Fund account. This is what you end up getting if you go into a TD Branch. My daughter thought she was opening a TD Direct Investing account. She did not.
If you fill in the form, you assume that you can then buy E-series funds. They even show up in your list of funds that you can buy. However, that is incorrect.
The E-series funds are Index funds with low MER fees. I use them in many of my accounts as full disclosure. I am not receiving any compensation for talking about them. Many different websites have talked about them and how useful they are, but they are tricky to use in a TD Mutual Fund account.
A TD Mutual Fund Investing Risk Profile is completed when the account is opened, and periodically after that (every year or two), it is updated. The profile questions usually push folks into a lower risk Balanced profile, and evidently, the E-series funds are far riskier.
The E-series Funds have turned into the red-headed stepchild of the TD Mutual Funds group. None of their staff seem to want to sell them or use them in any form. It is easier to use TD E-series funds in a Questrade account than a TD Mutual Fund account.
My opinion is that due to the E-series being lower cost, the TD Mutual Fund reps don’t make much money (if any) trading them. This makes the rep less motivated to use them. Why the TD Mutual Fund online system seems to default to E-series orders rejected is another issue.

Simple Solution to E-Series Orders Rejected ?
I will suggest a simple fix to TD Mutual Funds who adds the following “initial” block.
I allow the TD Mutual Funds group to alter my Investment Risk Profile to enable me to use the E-series funds in my investment portfolio.
Name: ________________ Initials: _____________
Seems straightforward to me. I doubt this will happen, it is too clear, and nobody makes money.
I’ve set up the accounts up twice once for my TFSA and again for an RESP Both times in branch with an advisor. When the risk profile part came up I just said please just click D for every single question so that I can send in my conversion request form. I was asked once about purchasing a balanced fund instead and I answered this is my money I’m going to invest it in low cost ETF’s and balance it myself