Error: 'Fail to create pixmap with Tk_GetPixmap in TkImgPhotoInstanceSetSize' when executing plt.subplots()

Question

When i executing this function i get this error: Fail to create pixmap with Tk_GetPixmap in TkImgPhotoInstanceSetSize. This error occur in this line: fig, ax = plt.subplots()(line 12). The strange thing is, that this error only occur sometimes (Maybe only 10% of their executes). Here is my whole function:

from bs4 import BeautifulSoup
from PIL import ImageDraw, Image, ImageFont
from colour import Color
import base64
from io import BytesIO
import matplotlib.pyplot as plt

def getCurrentBatterySOCImage(batterySOC):
   red = Color("red")
   colors = list(red.range_to(Color("#23b818"), 101))
   color = colors[round(batterySOC)].hex
   fig, ax = plt.subplots(facecolor="black")
   ax.set_facecolor("black")
   fig.tight_layout()
   ax.axis("off")
   ax.bar([1], batterySOC, color=color)
   ax.axis([0.6,1.4,0,100])
   ax.set_aspect(.02)

   tmpfile = BytesIO()
   fig.savefig(tmpfile, format="png", pad_inches=0, bbox_inches="tight")
   plt.close(fig)

   bar = Image.open(tmpfile)
   bar = bar.resize((107, 208))
   img = Image.new("RGBA", (136, 248), (255, 0, 0, 0))
   img.paste(bar, (14, 26), bar)
   battery = Image.open("img/battery.png")

   img.paste(battery, (0, 0), battery)


   font = ImageFont.truetype('font/RobotoMono.ttf', 40)
   message = f"{batterySOC}%"

   draw = ImageDraw.Draw(img)
   w, h = draw.textsize(message, font=font)

   draw.text(((136-w)/2, (248-h)/2), f"{batterySOC}%", fill=(255, 255, 255), font=font, stroke_width=2, stroke_fill="black")

   tmpfile1 = BytesIO()
   img.save(tmpfile1, format="png")
   encoded = base64.b64encode(tmpfile1.getvalue()).decode('utf-8')

   with open("index.html") as fp:
       soup = BeautifulSoup(fp, "html.parser")
       soup.find("img", attrs={'id': 'battery'})['src'] = f"data:image/png;base64,{encoded}"
   with open("index.html", "w") as fp:
       fp.write(soup.decode())
   return

Can someone help me to fix this?

Answer 1

This seems to be a memory issue from this issue, new in Matplotlib 3.5 (vs 3.3)

The recommended way is to switch to 'Agg' backend if possible

[EDIT] Issue is now resolved with default backend in newer versions of Matplotlib: 3.6 (sept 2022), 3.7... If possible, as per wisbucky answer you may upgrade lib:

pip install --upgrade matplotlib