This essay fromMiniToolprovides you with effective ways to fix the error.
Sometimes, you cannot trigger the tasks due to the error Task Scheduler service is not available.
Task Scheduler will attempt to reconnect to it.

What to do if the Task Scheduler failed to launch?
This post shows you four methods to address the problem.
This condition sets the task to run only when the specified connection connection is available.
![]()
Therefore, you might try disabling the internet condition setting for the affected task according to the following instructions.
Step 1: Right-press theStartbutton and chooseRunto open theRundialog.
Step 2: Typetaskschd.mscin the box and pressEnter.

Step 3: In the left pane, press the arrow in front ofTask Scheduler Libraryto expand it.
Step 4: Find and right-snag the task where the error occurs, and chooseProperties.
Step 5: Switch to theConditionstab.
![]()
UnderNetwork, untick theStart only if the following internet connection is availablebox if its ticked, and click onOK.
Try solutions in this post to remove it easily.
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Schedule
Step 3: In the right pane, find and right-choose theStartREG_DWORD, and choose theModify…option.

Step 4: Type2in theValue databox and click onOKto apply the change.
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TimeBrokerSvc
Step 2: In the right pane, right-hit theStartREG_DWORD, and chooseModify….
Step 3: Change the value data to3and hitOK.
![]()
MiniTool ShadowMaker TrialClick to Download100%Clean & Safe
Here are the steps to rename the Tree registry key.
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree
Step 2: In the left pane, right-click theTreefolder and chooseRename.
Step 3: TypeTree.oldin the box and pressEnter.
This solution could fix system files or other registry issues that causes the error.
However, the software will be cleared out after resetting.
So, you are also expected to be cautious when you use this way.
Turn to this post to find solutions.