Against which Lazarus version are you testing? We are testing against Lazarus 2.0.12 with FPC 3.2.0. Tzseconds is a variable inside unixutil, can you confirm this? We have tested in Ubuntu 20.04.2 LTS. Tzseconds has been added a while ago, since last year so it's unclear why suddently this is an issue. We can only suspect that this is an issue in Lazazrus/FPC.