Common when using mods the server may crash and you will find a line in the logs which as an example will say:
"Total edicts: 2049
Engine error: ED_Alloc: no free edicts"
That error comes when you have hit the limit of dynamic entities. For example: point_spotlight is a dynamic one where light_spot isn't (unless you name it). func_brush is also a dynamic one.
This is common when using mods. The only way to get around this is to delete the entities which are using up the slots.
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