You're trying to update your MR6400v5, but it's telling you that the file is not correct? Did you try to redownload the file again? it sounds like you got a bad file or the file got corrupted somehow

  @M585583 yes i trying download sometimes, but it still cant update

my current firmware is below:

 

Thanks.

  @AJDMS 

Looks like you have EU v5.0 of MR6400 like mine TL-MR6400(EU) ver 5.0 (look for model detail on the white part at the back of your router just above S/N serial numbers ) if its working fine not giving you any/specific problem i suggest you refrain from updating coz it might mess up your router

 

But if you have a problem with receiving sms but not showing in inbox or you need to be able to select LTE bands manually or ussd not functioning correctly you can try the below firmware

 

https://static.tp-link.com/2020/202012/20201208/TL-MR6400(EU)v5_1.1.0_0.9.1_%5b201113-rel63736%5d_up_boot_all_2020-12-08_09.38.45.zip

 

Its a beta firmware not stable use at your own risk but it solved all of the above issues for me hope its going to work for you as well