Dear Dales & iuv,

I think it has several reasons for this js or style sheet error.

I got a workaround for the same, (Even I am not recommending this, but try it )

1. in config file (odoo.conf file)of odoo change memory allocation (Even you are not configured the memory allocation yet)
   

   replace the below argument if you already configured or add new argument if didn't configure yet.
   
   

   limit_memory_hard: 2684354560

   limit_memory_soft: 2147483648
   
   

2. Make sure that you are installed the less package, In ubuntu, go to terminal and hit the below--
   sudo npm install -g less@3.0.4 less-plugin-clean-css
   
   

3. Then restart your odoo server.
   
   
   Hope it is working fine.
   I got the solution for v10 to v13 with this.
   
   Thank You