@gaaf: have you set the `acc_param` function to empty string? The condition is also with `uacred_acc_fct_s.s[0] != '\0'`.
In 5.5, the condition was similar, snippet next:
``` if(rd_acc_fct == 0) { /* import the acc stuff */ if(acc_fct_s != 0 && acc_fct_s[0] == '\0') { fct = find_export(acc_fct_s, 2, REQUEST_ROUTE); if(fct == 0) fct = find_export(acc_fct_s, 1, REQUEST_ROUTE); if(fct == 0) { LM_ERR("cannot import %s function; is acc loaded and" " configured\n", acc_fct_s); return E_UNSPEC; } rd_acc_fct = fct; } } ```
The `acc_fct_s` was renamed to `uacred_acc_fct_s` in 5.6.