Start process link not displayed because the system is in a degraded (stateless) status

Hello,

I have the following error from web browser interface (NOT MOBILE):

"Start process link not displayed because the system is in a degraded (stateless) status" , when a user press on a  a!linkField( links: {a!startProcessLink(....

I saw that there are some problems with it explained here: https://community.appian.com/support/w/kb/1338/kb-1867-start-process-link-not-displayed-because-the-system-is-in-a-degraded-stateless-status-error-when-starting-processes-in-the-appian-for-mobile-devices-app but I don't have a mobile interface is a simple interface exposed as a report in sites.

(ps: appian version  used 18.3)

Can someone give a clue what can I do? 

kind regards,

ana