Please help us help you and fill where relevant:
Your LimeSurvey version: 5.6.28
Own server or LimeSurvey hosting: Own server
Survey theme/template: Custom template
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Hi there,

We are upgrading from version 3.x to 5.x and I had a question about where custom plugins should be saved. I found some documentation for version 4.x that said custom plugins should be saved to the /upload/plugins folder. Is this still the case for 5.x? In our version 3 install we had them saved in the /application/plugins directory. 

Thanks!

/upload/plugins is the correct folder, as it shouldn't be overwritten and backup when updating.

I think this would also been the correct folder already in LS 3 and before.