Solved checksum verification failed on update

Hello,
I've had an issue for a few months that I cannot solve. When trying to update Kunena from version 5.2.5 to 5.2.6 I get this error:

Error
The checksum verification failed. Please make sure you are using the correct update server!
Error updating package.

The only difference from the previous updates was that I had to rebuild the Update sites since Kunena was not showing up in the available updates list. All else remains the same and other updates (e.g. Joomla, Community Builder) updated without issues. 

The updates site listed in the Updates Sites is  update.kunena.org/5.2/list.xml  

I have tried going through the web install, and I get an error there "There was an error", nothing more. If I download the package directly from here and manually update by uploading the file, I get the same checksum error. 

I cannot think of other options. Any help would be appreciated. 
Thank you,
Tomás

System Information

Hello,

Do-you tried only with Joomla! updater or you have tried by uploading  the zip of kunena 5.2.6 ?

Hi,
Thank you for answering. I was able to solve it. It was a permissions issue on an install folder that had gone awry. 
Thanks
Tomás