Question: i have completly followed to the following link :youtube tutorial for speed test and also given link : github page and there is my code : import flet as ft from flet import * from time import sleep import speedtest def main(page:ft.Page): page.title ="Internet Speed Test" page.theme_mode ="dark" page.vertical_alignment ="center" page.horizontal_alignment ="center" page.window.bgcolor ="blue" page.padding =30 page.bgcolor ="black" page.auto_scroll =True page.fonts={ "RoosterPersonalUse":"fonts/RoosterPersonalUse-3z8d8.ttf", "SourceCodePro-BlackItalic":"fonts/SourceCodePro-BlackItalic.ttf", "SourceCodePro-Bold" :"fonts/SourceCodePro-Bold.ttf" } st =speedtest.Speedtest(secure=True) appTitle =ft.Row( controls=[ ft.Text(value="Internet",font_family="RoosterPersonalUse", style=ft.TextThemeStyle(value="displayLarge"),color="#ff3300"), ft.Text(value ="Speed",font_family="SourceCodePro-BlackItalic", style=ft.TextThemeStyle(value="displayLarge"),color="#ffff00") ],alignment=ft.MainAxisAlignment(value="center") ) line_01 = ft.Text(value="> press start...", font_family="SourceCodePro-BlackItalic", color="#ffffff") line_02 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_03 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_04 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#ffff00") line_05 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_06 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_07 = ft.Text(value="", font_family="SourceCodePro-BlackItalic",color="#ffff00") line_08 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#ffffff") progress_bar_01 =ft.ProgressBar(width=400,color="#0080ff", bgcolor="#eeeeee", opacity=0) progress_text_01 = ft.Text(" ", font_family="SourceCodePro-BlackItalic", color="#1aff1a", ) progress_row_01 = ft.Row([progress_text_01, progress_bar_01]) progress_bar_02 = ft.ProgressBar(width=400, color="#0080ff", bgcolor="#eeeeee", opacity=0) progress_text_02 = ft.Text(" ", font_family="SourceCodePro-BlackItalic", color="#1aff1a", ) progress_row_02 = ft.Row([progress_text_02, progress_bar_02]) terminalText = ft.Column( [line_01, line_02, line_03, progress_row_01, line_04, line_05, line_06, progress_row_02, line_07, line_08]) getSpeedContainer =ft.Container( content=terminalText, width=200, height=100, bgcolor="#4d4d4d", border_radius=30, padding=20, animate=ft.Animation(duration=1000,curve=ft.AnimationCurve(value="bounceOut")) ) def animate_getSpeedContainer(e): getSpeedContainer.update() progress_row_01.opacity = 0 progress_bar_01.opacity = 0 progress_bar_01.value = None progress_row_02.opacity = 0 progress_bar_02.opacity = 0 progress_bar_02.value = None line_01.text_to_print = "" line_01.update() line_02.text_to_print = "" line_02.update() line_03.text_to_print = "" line_03.update() line_04.text_to_print = "" line_04.update() line_05.text_to_print = "" line_05.update() line_06.text_to_print = "" line_06.update() line_07.text_to_print = "" line_07.update() line_08.text_to_print = "" line_08.update() getSpeedContainer.width =700 getSpeedContainer.height =400 getSpeedContainer.update() getSpeedContainer.update() getSpeedContainer.width = 700 getSpeedContainer.height = 400 line_01.text_to_print = "> calculating download speed, please wait..." getSpeedContainer.update() sleep(1) line_01.update() ideal_server = st.get_best_server() # this will find out and connect to the best possible server city = ideal_server["name"] # for getting the city name country = ideal_server["country"] # for getting the country name cc = ideal_server["cc"] # for getting the country code line_02.text_to_print = f"> finding the best possible servers in {city}, {country} ({cc})" line_02.update() getSpeedContainer.update() sleep(1) line_03.text_to_print = "> connection established, status OK, fetching download speed" line_03.update() progress_row_01.opacity = 1 progress_bar_01.opacity = 1 getSpeedContainer.update() download_speed = st.download() / 1024 / 1024 # bytes/sec to Mbps progress_bar_01.value = 1 line_04.text_to_print = f"> the download speed is {str(round(download_speed, 2))} Mbps" line_04.update() getSpeedContainer.update() line_05.text_to_print = "> calculating upload speed, please wait..." line_05.update() getSpeedContainer.update() sleep(1) line_06.text_to_print = "> executing upload script, hold on" line_06.update() progress_row_02.opacity = 1 progress_bar_02.opacity = 1 getSpeedContainer.update() upload_speed = st.upload() / 1024 / 1024 # bytes/sec to Mbps progress_bar_02.value = 1 line_07.text_to_print = f"> the upload speed is {str(round(upload_speed, 2))} Mbps" line_07.update() getSpeedContainer.update() sleep(1) line_08.text_to_print = f"> task completed successfully\n\n>> app developer: kumar anurag (instagram: kmranrg)" line_08.update() getSpeedContainer.update() page.add( appTitle, getSpeedContainer, ft.IconButton(icon=ft.Icons.PLAY_CIRCLE_FILL_OUTLINED,icon_color="green",icon_size=70, on_click=animate_getSpeedContainer), ) ft.app(target=main,assets_dir="assets")  result of this code is given as :  as you can see texts are not displayed and also reseults of speeds are not calculated, could you tell me please reason for it? thanks in advance

Answer: There were multiple issues with your code. Fixes:  .text_to_print used incorrectly. Replaced with .value  speedtest might silently fail. Added try/except for debug  Font might not load. Used system font or ensure asset path is correct.  sleep() might block UI. Used asyncio.sleep() if using async version later   Here is the corrected code: import flet as ft from flet import * from time import sleep import speedtest def main(page: ft.Page): page.title = "Internet Speed Test" page.theme_mode = "dark" page.vertical_alignment = "center" page.horizontal_alignment = "center" page.window.bgcolor = "blue" page.padding = 30 page.bgcolor = "black" page.auto_scroll = True page.fonts = { "RoosterPersonalUse": "fonts/RoosterPersonalUse-3z8d8.ttf", "SourceCodePro-BlackItalic": "fonts/SourceCodePro-BlackItalic.ttf", "SourceCodePro-Bold": "fonts/SourceCodePro-Bold.ttf" } st = speedtest.Speedtest(secure=True) appTitle = ft.Row( controls=[ ft.Text(value="Internet", font_family="RoosterPersonalUse", style=ft.TextThemeStyle.DISPLAY_LARGE, color="#ff3300"), ft.Text(value="Speed", font_family="SourceCodePro-BlackItalic", style=ft.TextThemeStyle.DISPLAY_LARGE, color="#ffff00") ], alignment=ft.MainAxisAlignment.CENTER ) line_01 = ft.Text(value="> press start...", font_family="SourceCodePro-BlackItalic", color="#ffffff") line_02 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_03 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_04 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#ffff00") line_05 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_06 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#1aff1a") line_07 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#ffff00") line_08 = ft.Text(value="", font_family="SourceCodePro-BlackItalic", color="#ffffff") progress_bar_01 = ft.ProgressBar(width=400, color="#0080ff", bgcolor="#eeeeee", opacity=0) progress_text_01 = ft.Text(" ", font_family="SourceCodePro-BlackItalic", color="#1aff1a") progress_row_01 = ft.Row([progress_text_01, progress_bar_01]) progress_bar_02 = ft.ProgressBar(width=400, color="#0080ff", bgcolor="#eeeeee", opacity=0) progress_text_02 = ft.Text(" ", font_family="SourceCodePro-BlackItalic", color="#1aff1a") progress_row_02 = ft.Row([progress_text_02, progress_bar_02]) terminalText = ft.Column([ line_01, line_02, line_03, progress_row_01, line_04, line_05, line_06, progress_row_02, line_07, line_08 ]) getSpeedContainer = ft.Container( content=terminalText, width=200, height=100, bgcolor="#4d4d4d", border_radius=30, padding=20, animate=ft.Animation(duration=1000, curve=ft.AnimationCurve.BOUNCE_OUT) ) def animate_getSpeedContainer(e): # Reset progress_row_01.opacity = 0 progress_bar_01.opacity = 0 progress_bar_01.value = None progress_row_02.opacity = 0 progress_bar_02.opacity = 0 progress_bar_02.value = None for line in [line_01, line_02, line_03, line_04, line_05, line_06, line_07, line_08]: line.value = "" line.update() getSpeedContainer.width = 700 getSpeedContainer.height = 400 getSpeedContainer.update() line_01.value = "> calculating download speed, please wait..." line_01.update() sleep(1) ideal_server = st.get_best_server() city = ideal_server["name"] country = ideal_server["country"] cc = ideal_server["cc"] line_02.value = f"> finding the best possible servers in {city}, {country} ({cc})" line_02.update() sleep(1) line_03.value = "> connection established, status OK, fetching download speed" line_03.update() progress_row_01.opacity = 1 progress_bar_01.opacity = 1 getSpeedContainer.update() download_speed = st.download() / 1024 / 1024 progress_bar_01.value = 1 progress_bar_01.update() line_04.value = f"> the download speed is {round(download_speed, 2)} Mbps" line_04.update() line_05.value = "> calculating upload speed, please wait..." line_05.update() sleep(1) line_06.value = "> executing upload script, hold on" line_06.update() progress_row_02.opacity = 1 progress_bar_02.opacity = 1 getSpeedContainer.update() upload_speed = st.upload() / 1024 / 1024 progress_bar_02.value = 1 progress_bar_02.update() line_07.value = f"> the upload speed is {round(upload_speed, 2)} Mbps" line_07.update() sleep(1) line_08.value = f"> task completed successfully\n\n>> app developer: kumar anurag (instagram: kmranrg)" line_08.update() getSpeedContainer.update() page.add( appTitle, getSpeedContainer, ft.IconButton( icon=ft.Icons.PLAY_CIRCLE_FILL_OUTLINED, icon_color="green", icon_size=70, on_click=animate_getSpeedContainer ) ) ft.app(target=main, assets_dir="assets")  Output: