In July 2016 the Joomla Extensions Directory team announced that all extensions had to be installable through the Joomla Update feature. This meant that we had to adjust Jomres automatic update feature ( which had been working flawlessly since 2009 ) to use Joomla's process instead.
In most cases, this will work
When you use the Update link in the Jomres control panel you will be sent to the Joomla Extensions Update page.
From this page you will be able to update Jomres. Click on the checkbox next to Jomres and click Update. When you click on this button Joomla will install the webinstaller which will then be loaded, from there you can complete the upgrade by following the onscreen instructions.
It is recommended that you do not update Jomres at the same time as other extensions. Install each extension one at a time.
Troubleshooting
Step 1
Occasionally you may have problems in that Joomla doesn't recognise that there's an update for Jomres.
To resolve this, first visit Joomla -> Extensions -> Manage -> Update Sites
Check to see if this site is in the list :
http://update.jomres.net/service/tracking/list.xml
If it is, delete it.
Next use the Rebuild button at the top left.
Now go to Extensions -> Manage -> Update, and proceed with updating as above.
Step 2
If the previous process doesn't work, then the next thing you can do is use the Joomla "Install from Web" tab. Wait for the Joomla Exensions Directory extensions to load, then use the search feature to search for Jomres. Click on Jomres, then install from there. Jomres will upgrade itself from there.
Step 3
If all else fails, you can use the "Install from URL" tab, enter "http://updates.jomres4.net/com_jomres.zip" in the Install from Url field and click Check and Install.