Following the import instructions from your site, I enter all the WHMCS 5.3 information (user, pass, host, encryption key, etc) but I get this error:
The import completed but the following errors ocurred:
importClients: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '8' for key 'PRIMARY' on line 124
importContacts: There is already an active transaction on line 163
importTaxes: There is already an active transaction on line 163
importCurrencies: SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens on line 124
importInvoices: There is already an active transaction on line 163
importTransactions: There is already an active transaction on line 163
importPackages: SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens on line 124
importServices: There is already an active transaction on line 163
importSupportDepartments: There is already an active transaction on line 163
importSupportTickets: There is already an active transaction on line 163
importMisc: There is already an active transaction on line 163
And no, it doesnt look like it imported anything. Clients and packages are still at 0.