I've seen some threads/topics that were entitled "Failed to...".
eg. (the thread name from StackOverflow)
Failed to load the JNI shared Library
Is this grammatical? Why?
Nah, I don't see a reason why it's not grammatically correct. Why do you think it's not? It makes perfect sense to me.
If you're wondering whether it should be in Past of Present, the answer is:
The library was supposed to load, but it did not. Which means it fail-ed to do so.
If you're confused about the failed to, the answer is:
Failed to is indeed and unquestionably used for saying something did not do when it was supposed/expected to.
- The company did not meet last year revenue target. -> It just didn't. That's probably it.
- The company failed to meet last year revenue target. -> It didn't, and it was expected to succeed (to meet the revenue target).
If you're confused about the omitted subject (which usually appears before the verb in a sentence), the answer is:
English sentences often omit the subject, as long as the reader/listener knows the subject. And it is done in informal English, more often in spoken English. For example:
- I love you -> Love you (without the subject I)
- The program failed to load -> Failed to load (without the subject the program)
More importantly, technologies (programs, in this case) these days often save memory space by omitting unimportant words in communicating ('speaking', in a way) with users through GUI. Microsoft Office apps, or certain Websites, Browsers, for example, often remove 'unimportant' words which without the sentences are still understandable.
So.. Is that what you're confused about?
In standard English, the subject of a main clause declarative typically cannot be omitted. That makes your example incomplete; it is not a complete standard English sentence.
Of course, omitting the subject is probably okay here because:
You shouldn't write a sentence like this in an essay or on a test, but it's fine as an error message. It doesn't need to be a complete sentence, so there's nothing wrong with it.
Similarly, a street sign might read "NO U-TURN"—it's not a complete sentence, but it's still appropriate given the right context. It doesn't need to be a complete sentence.
(As an aside, Library here shouldn't be capitalized.)