Hello all,
Here is the setup.

For any new ticket, osTicket wants to assign an id already taken.
[INSERT INTO ost_form_entry_values
SET field_id
= 46, entry_id
= 19793]
Duplicate entry '19793-46' for key 'ost_form_entry_values.PRIMARY'<br /> <br />
---- Trace ----<br />
#0 C:\inetpub\wwwroot\osTicket\include\mysqli.php(207): osTicket->logDBError()<br />
#1 C:\inetpub\wwwroot\osTicket\include\class.orm.php(3482): db_query()<br />
#2 C:\inetpub\wwwroot\osTicket\include\class.orm.php(658): MySqlExecutor->execute()<br />
#3 C:\inetpub\wwwroot\osTicket\include\class.dynamic_forms.php(1535): VerySimpleModel->save()<br />
#4 C:\inetpub\wwwroot\osTicket\include\class.dynamic_forms.php(1377): DynamicFormEntryAnswer->save()<br />
#5 C:\inetpub\wwwroot\osTicket\include\class.dynamic_forms.php(1316): DynamicFormEntry->saveAnswers()<br />
#6 C:\inetpub\wwwroot\osTicket\include\class.ticket.php(4391): DynamicFormEntry->save()<br />
#7 C:\inetpub\wwwroot\osTicket\include\api.tickets.php(140): Ticket::create()<br />
#8 C:\inetpub\wwwroot\osTicket\include\api.tickets.php(202): TicketApiController->createTicket()<br />
#9 C:\inetpub\wwwroot\osTicket\include\class.mailfetch.php(76): TicketApiController->processEmail()<br />
#10 C:\inetpub\wwwroot\osTicket\include\class.mailfetch.php(126): osTicket\Mail\Fetcher->processMessage()<br />
#11 C:\inetpub\wwwroot\osTicket\include\class.email.php(1099): osTicket\Mail\Fetcher->processEmails()<br />
#12 C:\inetpub\wwwroot\osTicket\include\class.mailfetch.php(243): MailBoxAccount->fetchEmails()<br />
#13 C:\inetpub\wwwroot\osTicket\include\class.cron.php(25): osTicket\Mail\Fetcher::run()<br />
#14 C:\inetpub\wwwroot\osTicket\scp\autocron.php(61): Cron::MailFetcher()<br />
#15 {main}

Thanks for your help.
Best regards
Laurent