That's a litany of errors on the link: it points to the old wikispaces site (from when twallan ran the show), and the URL itself looks like it was encoded wrong.
Here is the link brappl posted, you have to view it through the WayBack Machine, and I've reproduced it below. I kept the source formatting as close as possible intentionally, apologies for weird indentations.
Most likely the sim has a broken or corrupt outfit assigned to them and when the game attempts to render their physical body, it is unable to do so.
For the solution to this problem, please see: DebugEnabler FAQ - Fix Invisible Sims.
TIP: Don't want to use NRaas? See:
The Invisible Sim Fixer Mod by ConsortThe Same Sim Keeps Getting StuckOverwatch generally corrects these issues but occasionally, circumstances prevent that from happening.
There are a couple of different things that can be done to fix this:
If you have ErrorTrap installed and a script error has been generated, you could upload the error for someone to read to see if it can be determined what is causing the sim to continue to be stuck.
See: How To Upload.
Temporarily turn off the Overwatch Stuck Check Auto Reset function so that Sim (and temporarily, any other sim, that may be stuck during this period) will stay at that unroutable spot when the notice appears. This way you can check the terrain or Lot and fix the routing problem (if possible).
Don't forget to turn the Stuck Check Auto Reset option back on again afterwards. CityHall/Computer > NRaas > Overwatch > Settings > Stuck Check Auto-Reset
Stuck Sims and JigsHere are a few suggestions for finding and flushing Jigs.
Jigs are objects used to temporarily alter the routing system. In the case of a SocialJigTwoPerson for instance, they stop sims from walking between two sims having a conversation.
They often pile up in the game causing routing issues, resulting in lag.
Often, those markers are generated by the game for spawning stray pets or as mentioned above. Social Jigs can cause the same type of problem. Deleting a jig that is in use will most likely bounce the sims involved. ErrorTrap should hard-reset them automatically every night, if you have that mod installed but under some circumstances it does not catch them all.
To find Jigs and flush (delete) them, use MasterController:
From City Hall or any computer: NRaas > Master Controller > Town > Object Stats
TIP: You can actually see some of the jigs as grey oval-shaped rugs if you're in BuyDebug mode. You can then pick them up and delete them.
If nothing else suggested above has worked try this:
Click on the ground > NRaas > Master Controller > Object Stats > Not Inventory then click on the jig, confirm flush and that should remove them.
If you want to check if it's a "worldly problem" use the City Hall and instead of "Not In Inventory", use "Global" to flush them all.