I analysed the error a little bit deeper.... and the reason is this:
I need to fix this in my plugin anyway, but you need to fix your gcode.
Line 216: G1 F{travel_speed}
Then you can also work with the current DLP-Version.
OK but do you mean that I have to remove G1 F{travel_speed} from my GCode ?
Because I'm using this pre-code almost for 2 years and I never face this issue.
Is it because I upgrade OctoPi / OctoPrint recently (I add to because plugins were not able to upgrade automaticaly anymore because of Python version) ?
The{travel_speed} is supposed to be replaced by your slicer (which was probably Cura at some point in the past). S3D doesn't use {}for its variables, it uses [] and I don't know if travel_speed is one of its variables (people have asked for a list of S3D variables but the developers have so far ignored the request).
The command itself may very well be a noop anyway as the feed speed (F) is changed often (see the rest of your start gcode).