I am trying to upgrade Joomla 2.5.28 to Joomla 3.x using the steps described here: https://docs.joomla.org/Joomla_2.5_to_3.x_Step_by_Step_Migration
I backed up the original website using Akeeba and resotred it into a sub-domain. All steps up till 6 seem to go through. Step 6 asks for changing the 'Update Server' under 'Options'. I am unable to do so. I select 'Short Term Support' from the drop-down menu, and click on 'Save'. I get a 'Configuration Successfully Saved' blue message but the value in front of 'Update Server' is reverted back to 'Long Term Suport'.
Anyone had a similar issue (and hopefully a solution)?
I tried to disable caching (as suggested on some forums) but it seems I am even not able to do so: under Site -> Global Configuration -> System I see 'Cache' is set to 'ON - Progressive Caching', I change it to 'OFF - Caching Disabled' and click on 'Save & Close'. But I get no reaction (and the setting is still 'ON' even if I log out and log back in).