downgrade
n.a change to a lower or less powerful level. In computing, it means replacing a newer version of software with an older one.
n.a reduction in rank, status, or quality; in a technical context, the substitution of a software or hardware system with an earlier or less advanced version.
“The software downgrade fixed the bugs in the new version.”
“After experiencing several system crashes, the IT department recommended a temporary downgrade to the previous stable release.”
“The credit agency's recent downgrade of the national debt has led to increased borrowing costs and a sharp decline in investor confidence across the region.”
Often paired with the preposition 'to' when indicating the target version or level.
From down- + grade.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.