There is one military lot in my town. My teen goes to school there and recently got a part-time ROTC job to fulfill the After School Employment opportunity. It's his last day of school before aging up and he keeps getting a script error upon entering the building. He's been attending the same school with no problems until now.

I thought it might be some sort of school/work conflict, so I canceled the opportunity and used MC to remove his job designation, but it keeps happening. I've reset the sim, the lot, and the entire town. I have not installed any new mods or removed any mods between my last play session and now. Any ideas on what's causing this?

Not sure how much you need from the error log, but I thought these were the relevant bits:

Log-Time: 03/05/2018 15:29:36 System.NullReferenceException: A null value was found where an object instance was required. #0: 0x00030 callvirt in Sims3.Gameplay.Careers.Sims3.Gameplay.Careers.GoToSchoolInRabbitHole:GetAfterschoolActivity (Sims3.Gameplay.Actors.Sim,Sims3.Gameplay.Careers.School,Sims3.Gameplay.Interfaces.ISchoolRabbitHole,bool&) (68D97B60 [49FBB400] [49AA1000] [00000000] [1237602900] ) #1: 0x00057 call in Sims3.Gameplay.Careers.Sims3.Gameplay.Careers.GoToSchoolInRabbitHole:InRabbitHole () () #2: 0x000b0 callvirt in Sims3.Gameplay.Abstracts.RabbitHole+RabbitHoleInteraction`2:Run () () #3: 0x000db stloc.u1 in Sims3.Gameplay.Interactions.Sims3.Gameplay.Interactions.InteractionInstance:RunInteractionWithoutCleanup () () #4: 0x00348 stloc.u1 in Sims3.Gameplay.ActorSystems.Sims3.Gameplay.ActorSystems.InteractionQueue:ProcessOneInteraction () () #5: 0x0011c stfld.u1 in Sims3.Gameplay.Actors.Sims3.Gameplay.Actors.Sim:DoInteraction () () #6: 0x00015 br.s in Sims3.Gameplay.Actors.Sims3.Gameplay.Actors.Sim:Simulate () () #7: 0x00027 leave.s in ScriptCore.ScriptCore.ScriptProxy:Simulate ()

Can't edit posts? I'll add that it seems to affect only that sim. I switched to another household and my test sim was able to attend the military school normally.

The error, what we can see of it this way, seems to be about an After School Activity. That's not the same thing as a part time job. Do you have Generations in play? As I recall, the ROTC actual part time job is not after school like the activities (clubs) are, I think it's on weekends.

In the future though, it would be better if you could please upload script errors in their entirety instead of pasting them into message posts.
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Ah, sorry. Thank you for helping regardless of my mistake.

You're right, it's something about the after school activity. He was in the sports club, which meets on Thursdays/Fridays and Thursdays are my current holidays, so I didn't run into it until now (Friday). The teen stage is set to 14 days so he should have had this problem last week as well, but I think I had to reset the household for something else and all the sims skipped their Friday school/job schedules.

Removing the activity allowed him to attend class.

Glad you narrowed down the issue, at least. For what it's worth, I've never been able to make After School Activities work for sims enrolled in the specialty Careers mod schools. My ongoing game is really old though, been playing it since late 2011, and things like this are bound to happen given the evolution of the mods alongside my gameplay. I found it satisfying to open the Careers School add-on module in S3PE (it's really just a tuning file) and change the hours of the specialty schools so that they run longer; I made most of the high schools run from M-F, 10-4. Since the specialty schools build skills anyway and there are plenty of tones to choose from while a sim is attending, that seemed like a happy compromise for me. If sims in let's say the Science or Culinary school really want to build Charisma, they can do so on their own time without having to join the Drama Club or whichever ones do that.