Some IT administrators, in an effort to free disk space, delete the Patches or Hotfixes folder after an update. Later, when a dependent patch runs, it looks for source files from SP21 v4 (like DLLs or configuration templates) and fails when they are not found.
Your base game has updated to Data Pack 7.0 via Steam, but your mod structure or Sider files are still configured for an older version. Step-by-Step Guide to Fix the Error cannot update the patch sp21 v4 was not found in the updated