Last Exception File Troubles

I can not figure out what is causing this last exception file error. MC Command Centre is the only thing I've downloaded in several days and it works just fine, but whenever I go to make my sims dance, I get a last exception error.

<root>
    <report>
        <version>2</version>
        <sessionid>c07adea0520a45665cfe0378</sessionid>
        <type>desync</type>
        <sku>ea.maxis.sims4_64.15.pc</sku>
        <createtime>2019-06-10 03:17:09</createtime>
        <buildsignature>Local.Unknown.Unknown.1.51.77.1020-1.200.000.389.Release</buildsignature>
        <categoryid>__init__.py:239</categoryid>
        <desyncid>c07adea0520a45665cfe0378</desyncid>
        <systemconfig/>
        <screenshot/>
        <desyncdata>Exception in Sim Timeline: Exception running Element (KeyError: 'get_joint_transform_from_rig: Joint name [(null)] was not found in the specified rig [efff676d282112d3.8eaf13de]. JointNameHash [0xea70165a]().')&#xD;
        Traceback (most recent call last):&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\scheduling.py", line 212, in simulate&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\animation\animation_element.py", line 1145, in _run&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\animation\animation_element.py", line 1061, in get_asm&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\interactions\base\interaction.py", line 5479, in get_asm&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\postures\posture.py", line 1470, in get_registered_asm&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\interactions\base\interaction.py", line 5461, in &lt;lambda&gt;&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\interactions\base\interaction.py", line 5511, in setup_asm_default&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\objects\slots.py", line 113, in get_surface_height_parameter_for_object&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\objects\slots.py", line 291, in position&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\objects\slots.py", line 284, in transform&#xD;
          File "T:\InGame\Gameplay\Scripts\Server\objects\slots.py", line 276, in location&#xD;
          File "T:\InGame\Gameplay\Scripts\Core\native\animation\__init__.py", line 239, in get_joint_transform_from_rig&#xD;
        KeyError: 'get_joint_transform_from_rig: Joint name [(null)] was not found in the specified rig [efff676d282112d3.8eaf13de]. JointNameHash [0xea70165a]().'&#xD;
        rtim=0</desyncdata>
    </report>
</root>

I have deleted several mods, deleting the localthumbcache and the last exception file each time, deleted the stereo I was trying to get my sim to dance to and replaced it, etc. Please help me, I don't know what's wrong. Thank you in advance!