Can not associate a new category to existing product. PS 9.0.1.

[Juan Manuel Diaz]

With initial data from installation, i create a new category, now I what to associate it with an existing product, but can not find how to do it... 

I already gone to Admin -> Catalog -> Products  then to Categories section, and click Add New Category button, but my previously created category does not appears even using the search text field, it only select categories from initial data from installation, no new categories.

What can I do.

[El Patron]

I hope this helps also welcome to PrestaShop.

How to correctly associate a category to an existing product

1. In the back-office go to Catalog → Products (or the equivalent in your language).
2. Find & edit the product in question.
3. Within the product editing screen, look for the “Categories” tab/section (often on the left or under “Associations”).
4. In that section you should see a list of categories already assigned to the product (including the “Default category”) and a search/selection field to add more.
5. Use the search box to locate the newly created category. Then tick/select the category and save the product.
6. After saving, check on the front‐end (and possibly clear cache) to ensure the product appears in the new category page.

If your new category doesn’t appear in the list

1. Confirm that your new category has been created (Catalog → Categories) and is active.
2. Ensure that the category is not hidden, has a valid parent (for example “Home” or another category).
3. Sometimes the back-office search filter in the product edit page doesn’t show all categories instantly — try clearing filters, or simply scroll through the category tree to locate it manually.
4. Clear any store cache (and browser cache) just in case the UI is stuck with old data.  admin-->advanced parms-->performance (top right clear cache)
5. Check for module or override conflicts: if you’ve installed any modules that affect category-product associations or modified the “Associations” tab, those may interfere.

⚠️ Version caution: You may be running a less-stable release

Another point worth mentioning: the version you’re using, PS 9.0.1, is effectively a developer/beta build even though it’s been publicized as “stable”. From what I’ve seen, many users are running into issues because of that.  I have also been building on 9.0.0 and 9.0.1 and even I am having issues, only because client DEMANDED I do it.  looooool

My recommendation: If this is a live store, consider downgrading or reinstalling to PS 8.2.3, which is widely regarded as the last solid, well-tested release. This will reduce the chance of chasing random bugs (including category association issues) introduced in the 9.x line. If you are testing 9.x for development or module preparation, that’s fine — but I wouldn’t rely on it yet for a production environment.