ESP32 board installation error for CRC mismatch

Add the link to arduino IDE>Files>Preferences>Additional Board Manager URLs:

https://dl.espressif.com/dl/package_esp32_index.json

Open Board Manager and search for ESP32.

Just edit the file C:\Users\Admin\AppData\Local\Arduino15\package_esp32_index.json in notepad++ or any supporting editor.

Delete the checksum details inside " " according to the version like 1.0.4 or else.

Save it and open board manager of arduino.

Now download the esp32 board manager file…

SANTU0007:
Save it and open board manager of arduino.

When you do that, it just downloads a fresh copy of https://dl.espressif.com/dl/package_esp32_index.json and overwrites your modified version at C:\Users\Admin\AppData\Local\Arduino15\package_esp32_index.json, so your edit accomplishes nothing. I suspect it is pure coincidence that the problem went away after you edited package_esp32_index.json.