When DUPLICATE PROC O/P TYPE CHECK is activated Endevor checks the Element Catalog file for existing entries. During this process, if it detects any entries for elements in non-existent environments it issues the IMGR254E message indicating the invalid environment name.
This situation is most often caused by removing an environment from C1DEFLTS without first removing the elements in it, either by deleting them or by moving or transferring them elsewhere, leaving the Element Catalog file with entries for elements that no longer exist in an environment that no longer exists.
The first point to note is that simply running BC1JCSYN will not fix this problem, because BC1JCSYN only synchronises those environments that are defined in C1DEFLTS, ignoring any environments that are not in C1DEFLTS.
The way around this is to temporarily reinstate the old environment, by allocating 2 empty MCFs (stage 1 and stage 2) and defining the environment again in C1DEFLTS, and then run BC1JCSYN in UPDATE mode. Since the MCFs are empty, BC1JCSYN will consider the Element Catalog file to be out of sync with the MCFs and will delete all these entries from it, thus removing all references to that environment.
When the job has run successfully the environment can be removed from C1DEFLTS once more and the empty MCFs deleted.