How do you correct the -1 error?

[MonitoZimpatikon]

My friend plays in 1.16.5 and when he wants to start minecraft with forge but does not leave it, we already tried to update forge at that moment but we have not tried it for a long time, even though I think that will not fix it, can someone help me with this? please (I used a translator in case something was not understood well)

[Luis_ST]

Unfortunately, I did not fully understand what's your problem
but the debug log would be a good start to find and solve your problem