I just tried a webhook widget with my Wemos D1, the Blynk example of sunrise and sunset was working fine. When I try to get next day electric prices from the entsoe.eu web page i did first get nothing.
Then i checked the size of the output from the page and it seems to be some 2800 characters so i just extended my message buffer a little 
to 3072 and the result was:
18:19:51.575 -> [2567] Connected to WiFi
18:19:51.575 -> [2568] IP: 192.168.1.155
18:19:51.608 -> [2568]
18:19:51.608 -> ___ __ __
18:19:51.608 -> / _ )/ /_ _____ / /__
18:19:51.608 -> / _ / / // / _ \/ '_/
18:19:51.608 -> /____/_/\_, /_//_/_/\_\
18:19:51.608 -> /___/ v0.6.1 on ESP8266
18:19:51.608 ->
18:19:51.608 -> [2577] Connecting to blynk-cloud.com:80
18:19:51.740 -> [2732] Ready (ping: 65ms).
18:19:52.071 ->
18:19:52.071 -> User exception (panic/abort/assert)
18:19:52.104 -> --------------- CUT HERE FOR EXCEPTION DECODER ---------------
18:19:52.104 ->
18:19:52.104 -> Panic core_esp8266_main.cpp:133 __yield
18:19:52.104 ->
18:19:52.104 -> >>>stack>>>
18:19:52.104 ->
18:19:52.104 -> ctx: cont
18:19:52.104 -> sp: 3fffefd0 end: 5ffffe00 offset: 0000
18:19:52.104 -> 3fffefd0: feefeffe feefeffe feefeffe 00000e71
18:19:52.137 -> 3fffefe0: 000000fe 00000000 00000000 00000000
18:19:52.137 -> 3fffeff0: 00000000 00000000 00000000 3ffeebc8
18:19:52.137 -> 3ffff000: 00000000 00000860 40100274 00000e71
18:19:52.137 -> 3ffff010: 3ffff090 3ffeea0c 3ffeea0c 402048e2
18:19:52.137 -> 3ffff020: 000dd4da 00000000 3ffefb94 4020493f
18:19:52.170 -> 3ffff030: 3ffff090 3ffeea0c 0000003e 402043c9
18:19:52.170 -> 3ffff040: 3ffff090 3ffeea0c 3ffeea0c 40203d6b
18:19:52.170 -> 3ffff050: feefeffe feefeffe 00000213 40203dab
18:19:52.170 -> 3ffff060: feefeffe feefeffe feefeffe 3fffff00
18:19:52.170 -> 3ffff070: 00000e71 3ffff090 3ffee9d4 40201883
18:19:52.170 -> 3ffff080: feefeffe feefeffe feefeffe feefeffe
18:19:52.203 -> 3ffff090: 30007776 783f3c00 76206c6d 69737265
18:19:52.203 -> 3ffff0a0: 223d6e6f 22302e31 636e6520 6e69646f
18:19:52.203 -> 3ffff0b0: 55223d67 382d4654 0a3e3f22 6275503c
18:19:52.203 -> 3ffff0c0: 6163696c 6e6f6974 72614d5f 4474656b
18:19:52.236 -> 3ffff0d0: 6d75636f 20746e65 6e6c6d78 75223d73
18:19:52.236 -> 3ffff0e0: 693a6e72 32366365 2e353233 3a313533
when i did expect more like:
<Publication_MarketDocument>
<mRID>6dd62232c34249368669ba8169b344b4</mRID>
<revisionNumber>1</revisionNumber>
<type>A44</type>
<sender_MarketParticipant.mRID codingScheme="A01">10X1001A1001A450</sender_MarketParticipant.mRID>
<sender_MarketParticipant.marketRole.type>A32</sender_MarketParticipant.marketRole.type>
<receiver_MarketParticipant.mRID codingScheme="A01">10X1001A1001A450</receiver_MarketParticipant.mRID>
<receiver_MarketParticipant.marketRole.type>A33</receiver_MarketParticipant.marketRole.type>
<createdDateTime>2020-09-06T13:59:16Z</createdDateTime>
<period.timeInterval>
<start>2020-09-06T22:00Z</start>
<end>2020-09-07T22:00Z</end>
</period.timeInterval>
<TimeSeries>
<mRID>1</mRID>
<businessType>A62</businessType>
<in_Domain.mRID codingScheme="A01">10YFI-1--------U</in_Domain.mRID>
<out_Domain.mRID codingScheme="A01">10YFI-1--------U</out_Domain.mRID>
<currency_Unit.name>EUR</currency_Unit.name>
<price_Measure_Unit.name>MWH</price_Measure_Unit.name>
<curveType>A01</curveType>
<Period>
<timeInterval>
<start>2020-09-06T22:00Z</start>
<end>2020-09-07T22:00Z</end>
</timeInterval>
<resolution>PT60M</resolution>
<Point>
<position>1</position>
<price.amount>29.65</price.amount>
</Point>
<Point>
<position>2</position>
<price.amount>28.32</price.amount>
</Point>
<Point>
<position>3</position>
<price.amount>27.98</price.amount>
</Point>
The page seems always send a full 24h set of next day prices despite of specified time intervals. Any good ideas how to proceed?