Please move the umbrello related files which has been uploaded to upload.kde.org/incoming to download mirror 'stable/umbrello/2.28.3' location and update the symbolic link 'stable/umbrello/latest' to 'stable/umbrello/2.28.3'
dir shasum file
src c855e995fe2ce7c966a62c91c12f4202f840b0a852e9d9bd2613a4dd8a5089fa umbrello-2.28.3-src.7z
win32 262c24884b45897271143f63a08fd02d9418117e67d8156cfb8b6c6ba34ec576 umbrello-mingw32-2.28.3-22.1-bin.7z
win32 808ed8bc3a21d79b7dedd43d9c6089f871b5f0ae58966ddaf132f658d4384939 umbrello-mingw32-2.28.3-22.1-debug.7z
win32 5e93f762f77405d62c24768a93aa90594628a9beebf5280240b28bd02ec9bb82 umbrello-mingw32-2.28.3-22.1-setup.exe
win64 f28763f8139b40484b4c9cadfa09c4bcb156e94d0bfb04d0b76ce1289747b993 umbrello-mingw64-2.28.3-95.1-bin.7z
win64 7e26e76929555157235b07c2d3d4623e7650596234ccf3958e7fe11df10efe4b umbrello-mingw64-2.28.3-95.1-debug.7z
win64 0488087eb302a1ae28a28cd16ba6a4d2fabf4f289fc2f292230200a36025d2d5 umbrello-mingw64-2.28.3-95.1-setup.exe