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

thankyou i took the mod out and family is loading ok

You only need to run the game with the fix in once. Save the game after that (new name), then you can remove the mod.

You need to do with with every save that has the issue though

Cirisimstarsi​ 

the problem im having is endless loading screen and game wont load at all the only way i can play the save is with a mod by Lumpinou called milestones fixes but i would like to be able to play my save family without relying on a mod 

lindamn1000​  Thanks for posting the lastexception file.  The error is related to missing milestones.  So you can either add back your custom content playmats, or you can add this mod:

https://www.patreon.com/posts/mod-milestone-81237568

It is possible that the original problem is different and that this one only surfaced when you removed your mods and cc.  So if it doesn't help, please provide a new lastexception, if the game creates one.

Oh also: 
I tried loading into a different household in that savefile - worked.
I tried moving out my family and load into the build mode of the lot: worked.
I tried editing my family in CAS: worked.
And I also tried putting my family on another lot to play with it on there: It did not work...

Here's the last expection txt that came after all that (of course I deleted the others before loading the game)...

<?xml version="1.0" ?><root>
<report><version>2</version><sessionid>610af256f3a41b8668d42419</sessionid><type>desync</type><sku>ea.maxis.sims4_64.15.pc</sku><createtime>2025-09-24 19:07:57</createtime><buildsignature>Local.Unknown.Unknown.1.118.242.1030-1.200.000.677.Release</buildsignature><categoryid>developmental_milestone_tracker.py:1114</categoryid><desyncid>610af256f3a41b8668d42419</desyncid><systemconfig/><screenshot/><desyncdata>Exception raised while processing zone spin up sequence: 'Object not found: 0xcdf3a7b7' (KeyError: 'Object not found: 0xcdf3a7b7')&#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 1206, in send_all_milestones_update_to_client&#13;&#10;  File "T:\InGame\Gameplay\Scripts\Server\developmental_milestones\developmental_milestone_tracker.py", line 1114, in _get_milestone_update_msg&#13;&#10;KeyError: 'Object not found: 0xcdf3a7b7'rtim=0&#13;&#10;Client Session Time: 14.63&#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: 13,550,0,6063&#13; &#10;Modded: False&#13; &#10;SystemInfo: Windows 11 10.0.26100 GPU: NVIDIA GeForce RTX 4070 Ti  32.0.15.7628, GUID: CBED7ED0-2D23-11F0-96D3-9CE732E7893F&#13; &#10;</desyncdata></report>
</root>

I copied this text from another person since they had the exact same issue as i had...

After updating my game im unable to load into my gameplay save. I can load the sims 4 normally to the main menu and into the world menu but after that i get stuck at the blue loading screen. Ive tried removing and adding mods. Ive tried making sure everything is updated. Ive tried creating a whole new save and it seemed to work so i saved the household from the old save to try add to a new save but that didnt work either (still stuck in loading screen). Ive also tried repairing the game and deleting and restarting the game but no luck.

I've also tried making a new Sims 4 folder by relocating the original one but still nothing.

I also tried just making a new sims in a new save file and was able to boot into the game. 
PLEASE HELP ME... It's my first legacy and I would HATE to start over 

GentleNik​ You may need to go through your mods. Start at Broken/Updated Mods & CC. Make a new thread if you need more support.

LIFE SAVER! Thank you

Thank you so much, for trying to help me! 🙂 Sadly his Mod didn't work, because now my game isn't even loading the main menu. (I've downloaded his newest version 3.0) This is the wildest overall bug I have yet experienced. And I never had a broken beyond repair game. I can now only pray that EA will address and fix it 😑

GentleNik​ 

still with only the milestone fix ?

Could be this issue: Frozen game/menu after ad | EA Forums - 12008756 

If not, best if you create a new thread in gameplay for that.