An unusual error code prevents the system from upgrading from previous Windows versions to present Windows 10. The new operating system that has been in development since Windows 8 and Windows 8.1 failed to meet users expectations. Being the OS that incorporates the desktop and touch-based features into one fanciful and compact system people want to do their upgrade as quickly as possible.
Image showing Error Code 80240020 at Windows Update
Windows reserves sent out to those whose systems qualify for free upgrade have long been indicating to get ready for the new Windows setup. Microsoft has been loading systems which got their reserves earlier with files needed to trigger the setup process. For those who haven't received theirs would need to be patient for Microsoft to gradually help them to usher in the latest Windows 10 operating system in the upcoming days or weeks.
During the time of checking for updates you might run into an issue that requires your attention beyond general troubleshooting. This is the type of issues that needs changes to be made to the system registry by the time when all exhaustive means of deleting files from the 'Download' folder of the 'SoftwareDistribution' in the Windows directory is no more yielding results.
To do that you'd have to follow the step-by-step guide below. It is rudimentary and quick in finding solution to the Windows error code 80240020.
Red indicating Windows key + R
STEP 1: Press Windows key + R to open 'Run' dialog.
Red arrows pointing to process
STEP 2: Type or copy and paste regedit into 'Run' and click 'OK' to continue.
Image of red arrows pointing to process
STEP 3: Double-click on 'HKEY_LOCAL_MACHINE', next on 'SOFTWARE' and 'Microsoft'.
Red arrows indicating process
STEP 4: Double-click on 'Windows' to expand it and next double-click on ' CurrentVersion' to expand it.
Image of red arrows pointing to process
STEP 5: Double-click on 'WindowsUpdate' to expand it and right-click on 'OSUpdate' to open a drop-down menu.
Process indicated by red arrows
STEP 6: Select 'New' and next 'DWORD 32bit Value' to create 'New value#' and rename it to 'AllowOSUpgrade'.
Image of red arrows pointing to process
STEP 7: Right-click on 'AllowOSUpgrade' and select 'Modify...'.
Red arrow showing where to enter Value data 1
STEP 8: Change the 'Value data' to 1 and click on 'OK'.
Image showing red arrows pointing to process
STEP 9: Click on 'File Explorer', select 'Desktop' from the right-hand side and click on 'Control Panel' to continue.
Red arrow pointing to Restart now button
STEP 10: Click on 'Check for update' and click on 'Restart now' button to restart the system and continue the upgrade process.