MQTT ERROR: rejected, not a valid topic format - When connecting to AdafruitIO

[rum-neutralo]

• Arduino board: ESP8266 D1 Mini
• Arduino IDE version: Platform.io Adafruit MQTT Library @ 1.0.3

Adafruit_MQTT_Subscribe slider = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/slider");

When i run:
mqtt.subscribe(&slider);
the Adafruit.IO MQTT Errors show
"MYUSERNAME/errors" => rejected, not a valid topic format ?

[rum-neutralo]

Seams to be a Problem together with another library
WiFiUDP ntpUDP; NTPClient timeClient(ntpUDP, "europe.pool.ntp.org", 3600, 60000); ...

Having removed the ntpUDP and NTPClient the subscription works

[Michiel van der Kraats]

I'm still seeing this in my sketch and I'm not using the ntpUDP and NTPClient libraries. How did you determine it was a problem with WiFiUDP ? My sketch uses MDNS which uses WiFiUDP though. I commented that out but I still get the same strange error "not a valid topic format".

[Brent Rubell]

Resolved by @mkraats on the forums

Ah, one should always be careful after dusting off old code. Apparently, I had used:

#define AIO_MYFEED "myfeedname"

But now, only:

#define AIO_PM25 "/feeds/groupname.feedname"

Seems to work.