The paper deals with problems in the post-implementation phase of management Enterprise Resource Planning (ERP) systems. Proper management of the system maintenance stage is a basis for efficient system development in terms of business needs. Based on the research and analysis of collected materials, it turns out that making a decision to upgrade the system is equally crucial. We present revealed mechanisms determining the post-implementation approach to upgrade or reimplement the ERP system. The main aim is to determine the methodology and difference understanding to achieve success in the post-implementation stage. The paper shows that the systemic approach to the maintenance stage of the ERP system affects its further decisions: upgrade or reimplement. It has a direct impact on future maintenance costs and the scope of new business demands. This research is an outcome of industry–academia collaboration and based on several developed implementation systems, achieved upgrade and reimplementation projects. Based on case study analysis, we show that reimplementation means an evolution of the current ERP processes rather than another attempt to “reimplement” an unsuccessful system implementation. On the other hand, upgrades are not only a tool or system actualization but the easiest way to bolster company sustainability and to have the information system up to date. The issues discussed in the article will be used to develop changes in the implementation methodology of ERP systems.

Mass customization production is a manufacturing process in which mass-produced products are modified according to specific customer needs. An example of such production is furniture production, where multiple options options for various components or features are available. Demand forecasting in mass customization industry is a difficult task for organizations and is both crucial for their profits and for market penetration. Unfortunately, the currently available tools are focused on more standard demand forecasts, which lack interpretable representation of information relevant for mass customization products. This is especially relevant for ERP systems, which are the backbone of modern manufacturing. We propose a forecasting method adapted to the needs of mass customization by focusing on demand prediction—not on finished products, but on key intermediate goods. Moreover, we provide a method for determining such goods. As an additional consequence we provide an implementation strategy that reduces the risk and time consumption when implementing forecasting in ERP systems. All the results are implemented as appropriate functionalities of a IFS Application ERP system.