Purpose-Enterprise Systems (ES) upgrade is fundamental to maintaining a system's continuous improvement and stability. However, whilst the extant literature is replete with research on ES upgrade decision-making, there is scant knowledge about how different decision processes facilitate this decision to upgrade. This paper aims to investigate and better understand these processes from an organisation perspective. Research approach-A qualitative survey design adopted, utilised a web-based questionnaire and semi-structured interviews to collect data from 23 large organisations. Data accrued was qualitatively analysed and manually coded to identify the various decision processes undertaken during ES upgrade decisions. Findings-Analysis results reveal complex interrelations between the upgrade drivers, the need to evaluate the new version's functionality and the upgrade impact. Understanding the interaction between these elements influences the upgrade decision process. Research limitations-The study proposes ES upgrade processes that support a decision to upgrade major releases. Further research is required to offer either similar or conflicting arguments on the upgrade decision-making and provide a probabilistic generalisation of the decision-making processes. Originality-The research offers a comprehensive and empirically supported methodical approach that embraces an evaluation of a new version's functionality, technical requirements and concomitant upgrade implications as intrinsic decision processes. This approach assists in the decisions to establish the upgrade need and determine the level of change, effort required, impacts and associated benefits.