So you're importing a pack and encounter an error, to fix it as smooth as possible it's important to diagnose the issue correctly. When importing a broken pack you should notice an error message at the top of the screen.
Clicking on the popup message will give more general information about the pack as well as the error Minecraft is encountering with it. It is important that you take note of the error list at the bottom of the opened page.
Now, head back to the website and try to select the corresponding issue. If it is not listed specifically on the site you can always select the 'other' option.
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