The final build message often says that a target failed. It may not identify the first compiler or linker error that caused the failure. Start at the first error associated with the failing target and retain the command immediately before it. Parallel builds can interleave output; a narrow repeat of the failing target may make the evidence easier to read.
Classify the stage
A missing header is an include/dependency question. An undefined reference is usually a link-stage question. A binary that builds but cannot load a library is a runtime dependency question. A running game that rejects a client packet is a protocol/runtime question. Each needs different evidence.
Build revision:
Host operating system and version:
Compiler and version:
Target architecture:
Target being built:
First relevant error:
Full command for that error:
Dependency/library involved:
Last known-working revision:
Smallest change since it worked:Reduce the investigation
Return to a known-working revision or keep it beside the failing build. Rebuild the smallest affected target. Check whether the missing dependency is meant to come from the project, a vendored directory or the operating system. Use documentation for the actual OS/compiler version instead of assuming that a command from an old forum thread is still current.
Do not start by disabling warnings, removing unknown functions or copying arbitrary libraries into a system directory. Those changes can hide useful evidence and make a later failure harder to reproduce. If a workaround is necessary, keep its diff separate from the original failing change.
What to post
Post the template above and a short text log covering the first error and its command. Include enough surrounding context to see the target, but remove secrets and private paths that are not relevant. Explain whether the failure happens before or after linking.
Background
A game/db compilation question is an example of this recurring support category. The workflow here is M2City editorial guidance; it does not prescribe an obsolete FreeBSD image or a specific compiler to every project.