There is no "mission.pbo".
There is a "dayz_private_1.epoch.chernarus.pbo" in a folder called "mpmissions" (in case you are running another map than Chernarus the name of the pbo will be different).
Once you open the pbo with pbo-manager you can extract the files packed into that pbo, for example by copy (right mouse button) in the pbo manager window and paste (right mouse button) into some windows explorer window - and add files or folders the other way round.
In your windows explorer you create a folder named "Scripts" (never tested if upper/ lower case does matter, to be on the safe side make it the same like in your error message), into that folder you put the file "repairactions.sqf". Then you copy the whole FOLDER in Windows explorer (right mouse button) and paste it into the pbo-manager window (right mouse button - click on the very top entry to paste).
Then you should have a folder in your "dayz_private_1.epoch.chernarus.pbo" named "Scripts", with "repairactions.sqf" inside. If that is the case you can close pbo-manager and upload the "dayz_private_1.epoch.chernarus.pbo" to the "mpmissions" folder on your server (Backup or rename the existing "dayz_private_1.epoch.chernarus.pbo" - just to be on the safe side.
But still the repairscript does not work correctly - as you probably know if you have read the whole thread....
There is a "dayz_private_1.epoch.chernarus.pbo" in a folder called "mpmissions" (in case you are running another map than Chernarus the name of the pbo will be different).
Once you open the pbo with pbo-manager you can extract the files packed into that pbo, for example by copy (right mouse button) in the pbo manager window and paste (right mouse button) into some windows explorer window - and add files or folders the other way round.
In your windows explorer you create a folder named "Scripts" (never tested if upper/ lower case does matter, to be on the safe side make it the same like in your error message), into that folder you put the file "repairactions.sqf". Then you copy the whole FOLDER in Windows explorer (right mouse button) and paste it into the pbo-manager window (right mouse button - click on the very top entry to paste).
Then you should have a folder in your "dayz_private_1.epoch.chernarus.pbo" named "Scripts", with "repairactions.sqf" inside. If that is the case you can close pbo-manager and upload the "dayz_private_1.epoch.chernarus.pbo" to the "mpmissions" folder on your server (Backup or rename the existing "dayz_private_1.epoch.chernarus.pbo" - just to be on the safe side.
But still the repairscript does not work correctly - as you probably know if you have read the whole thread....