When i upload my web part in app catalog, after install in dev site. I have following error:
How to solve this problem?
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Is your gulp server is running? Try to make https://localhost:4321/ as trusted url (browser options) and that will solve your problem.
Otherwise you can upload the scripts to document library and use in client side web part.
Also note you can use this for development, as you are using resource from your localhost. But when you move to production you need to host the scripts file somewhere accessible to everyone (a document library or CDN). To achieve this you can navigate to solution
config -> write-manifests.json and upadate
cdnBasePath property to CDN URL or Document Library URL (till folders in which your scripts are uploaded).