Hello,
i had the same error when connect to an other Wifi after i tryed another Wifi. I use "Wifi.disconnect();" before Wifi.begin, that works.

I might be a little late to the party here but I think you'll find this is caused by an ESP32 internal race condition.
When you timeout on your initial connection request (perhaps because you didn't wait long enough) the ESP32 is likely still attempting the connection in the background. Thus, when you retry you get this error becasue the ESP32 firmware is still busy.

To eliminate the issue, call the (blocking) function, WiFi.waitForConnectResult(), like this:

bool bgWiFiReady = false;
uint8_t ui8FinalState = WiFi.waitForConnectResult(); //blocking call (up to ~10s)
char* cpFinalState = "unknown";
if (ui8FinalState == WL_CONNECTED)
{
bgWiFiReady = true;
cpFinalState = "Connected";
}