So far 4.26 has been pretty stable for me, overall very satisfied. I do not use lightmass, or virtual textures.
Movie Player Crash
After playing a video file, a packaged project crashes.
Potential Critical Structure Failure Detected
Though, not yet conclusive but it appears that since 4.26, when having a datatable open, and a crash occurs the related DT structure is exposed to corruption. The error is unknown structure in BP_Name, here, stemming from node, get datatable row by name, can be fixed with refreshing these nodes.