Since updating from 4.94 to to 5.03 I've started to get these dialogs, although infrequently:
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MUSHclient
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Unable to create the plugin save state file: C:\data\games\Mush\worlds\plugins\state\8187039aa9fa0efc332b32bd-f973af093e715dece34dc25f-state.xml
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OK
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