No bindings installable at OH 2.4

Hi, I have just upgraded openhab 2.3 to 2.4. Now I find a problem I cannot solve yet: After trying to install several bindings, like yeelight or wol, I found that none of them is installing but, where word INSTAL or UNINSTAL used to appear at the right of the binding, now it is spinning a circle and never finish to be installed. I had rebooted my rpi. All bindings installed before upgrading are working fine.
It’s the second time I upgrade to 2.4 and I also thought it was may fail in upgrading. Please let me know if this is a unique issue or general one. I had even updated raspbian before doing openhab upgrading. Thanks in advance.

Have you tried Clear the Cache.

Thanks for your reply. I did not, but I will as I finish this message. I will follow your link steps. Thanks once from a newbie.