An "exec format error" means your system can't run the file you've tried to execute--usually because it's not in a format your system can understand. This typically happens when a binary is compiled for a different CPU architecture, like trying to run a 64-bit Intel binary on an ARM-based machine.

It's also common with scripts missing a proper interpreter declaration at the top--called a shebang line (e.g., #!/bin/bash). Without this line, the system doesn't know how to handle the script.

To fix the issue, check the file type using file and compare it with your system's architecture using uname -m. For scripts, add the correct shebang line and make sure the file is executable (chmod +x). If the problem is a binary mismatch, you'll need to recompile it for your platform or run it using a compatible tool like an emulator or Docker with the right architecture setup.