In the daily work with WordPress and Co, the same problems occur at intervals again and again. Below I note the most important and immediately give the appropriate solution for it.
This solution must not always be clean. This means that there can also be better solutions for the respective problem. However, an overall view is always necessary. In the solutions presented here, the corresponding solution approach was autonomous. The use of the solutions presented here, is of course at your own risk. I strongly advise to make a backup beforehand. Due to updates (core, theme, plugins), it is also possible that one or the other code no longer works completely.