Unable to Produce Frame

Can you please share your system info? Like OS and version, CPU, RAM, GPU vRAM, Pr version? Thanks. Also a screen grab of your issue will be helpful.

There's not a lot to go on here. Does the error give you any other information? If not, while in Media Encoder, go to File > "Show Log" and go to the very bottom. You can also try File > "Show Errors" to see if anything helpful is in that log. Is there a timecode that gives you a hint as to what the problematic frame is? Also, does this error happen at the same point in encoding every time?

Instead of sending your comp to AME, what happens if you export it directly via AE's Render Queue. If you're new to AE then don't worry too much about all those settings, just start with the default Lossless Output Module—just know that it will create a very large file which you can then take into AME and convert to your deliverable. This is a very common way of exporting from After Effects and it will actually export much faster than if you're exporting directly to H.264 via AME.