HFI Calculator: Pathfinder SSO Login Error

**Actual Behaviour**

DW is getting an Pathfinder SSO Login Error and HTTP Status 400 - Bad Request when attempting to access HFI calculator (see attached files). This issue showed up in early November about the same time WF1 stopped calculating Fire Weather Indices. D. can eventually login to HFI Calculator after several attempts. I asked D. five follow-up questions and have included his responses.

1. Please confirm you are accessing HFI Calculator with the following URL: https://psu.nrs.gov.bc.ca/hfi-calculator
Yes
2. What browser are you using? Chrome is recommended.
Chrome
3. Were you switching between IDIRs when the issue occurred? There is a known login issue that sometimes occurs when switching IDIRs.
No
4. Did the issue occur immediately after navigating to the login page or was the login page open on your browser for > 5 minutes before you attempted to login in? A browser timeout on the login page could explain the issue.
No, attempted to login immediately.
5. Has the issue occurred on multiple occasions, i.e.) different dates? If the issue is recurring we can eliminate server down time as a possible explanation.
Occurred multiple times over multiple dates. I have found that closing the browser down and reopening will allow for me to open the page, but not always.

**Steps To Reproduce**

1. Navigate to https://psu.nrs.gov.bc.ca/hfi-calculator
2. Login to HFI Calculator using DW's personal IDIR

**Screenshots**

Two screenshots have been attached as PNG files.

**Expected Behaviour**

D. should not see any error messages when logging into HFI Calculator with his personal IDIR.

Start by reproducing the login flow at https://psu.nrs.gov.bc.ca/hfi-calculator in Chrome with a personal IDIR, using the reported repeated-attempt scenario. Use the attached screenshots and the HTTP 400 response to trace the failure. Done means the reported user can log in without Pathfinder SSO or HTTP 400 errors.

Written by the indexing model from the issue text.