Boot error occurred after downgraded Robotware 6.06 in IRB14000.

Since some control program was made using the old "arm-Angle definition," I tried to downgrade the existing Robotware in Yumi from 6.08 to 6.06, but the downgrade failed. The wrong code is shown in the figure. The Robotware version I use is downloaded was from Add-ins. The interesting thing is that I was able to use versions 6.08 and 6.10 of add-ins to boot without any errors.
I suspect that there is a problem with absolute accuracy. Are there any other solutions or ideas that could lead to a successful downgrade? Thanks in advance for all the discussion and answers.