# Side Effects After having run a Shopware migration (say from Shopware 5 to Shopware 6), sometimes "funny" thinsgs happen. Products are not visible in the storefront, or they are displayed but can't purchased. Things like this - I call them "side effects". ### max\_purchase = 0 in Shopware 5 max\_purchase = 0 is a valid setting in Shopware 5 for articles and simply means that a customer can purchase a number of items of a product limited only by available stock. However, after migration, max\_purchase = 0 in Shopware 6 means that a customer cannot purchase even a single item of this product. As a result, you will see `ProductOutOfStockError` errors ("The product \ is no longer available") in your logs when trying to a add the product to the cart. In the storefront on the product detail page you will note that the product cannot be added to the cart at all (the 'Add-to-basket' button is hidden). To solve this problem with a quick fix, run this SQL after migration (as always, backup your DB before): ```sql UPDATE product SET max_purchase = NULL WHERE max_purchase = 0; ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://notebook.vanwittlaer.de/migration/side-effects.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.