Re: [CC and Milestones, error code 110-578ef827] Stuck On Loading Screen Sims 4

Exact same issue. Loading screen loads, music plays - loading screen keeps loading indefinitely. 

and no custom content. 

At one point, the household I was trying to get into let me do it once, and then when I exited, the indefinite loading screen 

having the same issue but only on one lot. i can load into the game just fine but every time i try to leave the lot i'm stuck on an infinite loading screen. also no custom content.

cdkscully​ c6d90de81b5b1f49​ athorra​  Please open Documents > Electronic Arts > The Sims 4 and delete any lastexception files you see there.  Try again to load the affected household, or travel, and when you get stuck on the loading screen indefinitely, look for a new lastexception.  (You can close the game after a couple minutes.)  If you find one, open it, copy its text, and paste it into a reply here.

Please (continue to) test with your Mods folder removed.

Mine is now running after I added this mod:
https://www.patreon.com/posts/mod-milestone-81237568

That was one of the errors in the file. 

I'm adding back my CC one at a time. 

This was one of the Lastexception files:

<?xml version="1.0" ?><root>
<report><version>2</version><sessionid>3677af263c9f7d8869321f07</sessionid><type>desync</type><sku>ea.maxis.sims4_64.15.pc</sku><createtime>2025-12-04 18:55:59</createtime><buildsignature>Local.Unknown.Unknown.1.120.117.1030-1.200.000.685.Release</buildsignature><categoryid>developmental_milestone_tracker.py:1116</categoryid><desyncid>3677af263c9f7d8869321f07</desyncid><systemconfig/><screenshot/><desyncdata>Exception raised while processing zone spin up sequence: 'Object not found: 0x87ca43c0' (KeyError: 'Object not found: 0x87ca43c0')&#13;&#10;Traceback (most recent call last):&#13;&#10;&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Core\sims4\utils.py", line 179, in wrapper&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\areaserver.py", line 222, in c_api_server_tick&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 512, in update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone_spin_up_service.py", line 1767, in update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone_spin_up_service.py", line 1399, in on_update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 741, in on_hit_their_marks&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 1142, in _set_zone_state&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Core\sims4\callback_utils.py", line 158, in __call__&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\developmental_milestones\developmental_milestone_tracker.py", line 1208, in send_all_milestones_update_to_client&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\developmental_milestones\developmental_milestone_tracker.py", line 1116, in _get_milestone_update_msg&#13;&#10;KeyError: 'Object not found: 0x87ca43c0'rtim=0&#13;&#10;Client Session Time: 23.99&#13; &#10;Num Save Errors: 0&#13; &#10;Num Load Errors: 0&#13; &#10;Current Game State: 0x96d01090&#13; &#10;LoadingScreenActiveFlag: 1&#13; &#10;Origin Version: 13,608,0,6121&#13; &#10;Modded: True&#13; &#10;SystemInfo: Windows 11 10.0.26100 GPU: NVIDIA GeForce RTX 4060 Laptop GPU nvldumdx.dll 32.0.15.6094, GUID: D7B71E3E-6BA0-11CF-D463-5C1B0EC2ED35&#13; &#10;</desyncdata></report>
</root>

Was my previous response removed? 
I posted the lastexception file and also the mod fix that helped. 

My new lastexception is this. I tried the mod suggested by cdkscully​ but didn't work for me. 

<?xml version="1.0" ?><root>
<report><version>2</version><sessionid>a004708b2316e25f6932cd5a</sessionid><type>desync</type><sku>ea.maxis.sims4.15.macx86</sku><createtime>2025-12-05 13:18:55</createtime><buildsignature>Local.Unknown.Unknown.1.120.117.1230-1.200.000.685.Release</buildsignature><categoryid>developmental_milestone_tracker.py:1116</categoryid><desyncid>a004708b2316e25f6932cd5a</desyncid><systemconfig/><screenshot/><desyncdata>Exception raised while processing zone spin up sequence: 'Object not found: 0x8b28c1ca' (KeyError: 'Object not found: 0x8b28c1ca')&#13;&#10;Traceback (most recent call last):&#13;&#10;&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Core\sims4\utils.py", line 179, in wrapper&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\areaserver.py", line 222, in c_api_server_tick&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 512, in update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone_spin_up_service.py", line 1767, in update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone_spin_up_service.py", line 1399, in on_update&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 741, in on_hit_their_marks&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\zone.py", line 1142, in _set_zone_state&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Core\sims4\callback_utils.py", line 158, in __call__&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\developmental_milestones\developmental_milestone_tracker.py", line 1198, in send_all_milestones_update_to_client&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\developmental_milestones\developmental_milestone_tracker.py", line 1116, in _get_milestone_update_msg&#13;&#10;KeyError: 'Object not found: 0x8b28c1ca'rtim=0&#13;&#10;Client Session Time: 14.07&#13; &#10;Num Save Errors: 0&#13; &#10;Num Load Errors: 0&#13; &#10;Current Game State: 0x96d01090&#13; &#10;LoadingScreenActiveFlag: 1&#13; &#10;Origin Version: 13,608,0,6121&#13; &#10;Modded: False&#13; &#10;SystemInfo: Mac OS X Version 12.7.6 (Build 21H1320) GPU: AMD Radeon R9 M370X macOS Metal driver 0.0.0.0&#13; &#10;Architecture: x86_64&#13; &#10;&#13; &#10;</desyncdata></report>
</root>

cdkscully​  Your post may have been caught by the spam filter.  It's back now.

c6d90de81b5b1f49​  The error in your lastexception is also the milestone-related issue, so the mod should fix things for you as well.  Are you sure you enabled mods after adding this one? I ask because a couple other players who had this same error and thought the mod wasn't helping them have realized later they still had mods disabled.

I did re-enable mods and restart the game. I will try re-downloading when I have time to fiddle with it, something else must have gone awry. Thanks for your help so far :)

c6d90de81b5b1f49​  If the mod still doesn't help, please post a new lastexception.

Ahhh Got it!

So far that mod is working for me - my lastexception error had "milestone" in it so I searched for that. 

Thank you though! 

Re-downloading worked and the household now loads correctly again 👍