Primavera P6 Professional v17.x with Oracle client 12c upgrade to P6 20.12.12 and Oracle client v19

Hi

We are facing a problem while upgrading our Primavera P6 Professional client v17.12.3 with Oracle client 12c to P6 v20.12.12 and Oracle client v19.3 In fact I've got 2 versions on my PC installed: primavera p6 v17.12.3 and P6 20.12.12, with Oracle client 12c. Both works fine, but if I install the Oracle client 19c on top of it(uninstalling the 12c)-it doesn't work. Each connection string under Database configuration is marked with red color like sth was not right with its format(test button and others are disabled) But that is not true, the connection string is good and works