I am just starting to set up accounting in Odoo online (free version) But am getting problems that have halted my progress.

1/ Fiscal year:  Error message: "The name of the period must be unique per company!"

I have tried various different names, still getting same message.

2/ I generated a sales invoice on a test account, tried to print it & it comes back with Odoo server error, followed by lines of code!

3/ I ran a Tax report to check that the sales tax was shown but it is not.

Most of the online documentation differs from what I have in V8. Problems in set up I have encountered are not covered.

I have a suspicion that the problems may be to do with the chart of accounts but have been unable to find enough detail on configuration. the user guide just says that it (preconfigured UK chart) will need some configuation without specifiying what!  It starts well with good details & stops abruptly at the critical point.

I think my only chance of progressing with this is either some help of more than one sentence or a comprehensive user guide.  Any suggestions please.