In the TCustomPgDataSet.Execute(PgAccess) becomes TCRConnection.FAutoCommit(CRAccess) set to false and not reset after the exception in the RefreshRecord.

Then the error dialog, through our THauptForm.ShowServerTimer a ConnectionCheck with "Select true," starts in the TPgSQLCommand.Execute(PgClasses) a transaction, because still Connection.AutoCommit on false and then it provokes exceptions everywhere:

Bugfix proposal:

procedure TCustomPgDataSet.Execute;
var
  AutoCommitChanged: boolean;
begin
  AutoCommitChanged := ChangeAutocommit;
  try
    inherited Execute;
  finally
    if AutoCommitChanged then
      Connection.AutoCommit := True;
  end;
end;

procedure TCustomPgDataSet.Execute(Iters, Offset: integer);
...
//similarity