'Can you make any sense of Dockers error-messages?

I admit, I am a newbie in the container-world. But I managed to get docker running on my W10 with WSL2. I can also use the docker-UI and run Containers/Apps or Images. So I believe that the infrastructure is in place and uptodate. Yet, when I try even the simplest Dockerfile, it doesn't seem to work and I don't understand the error-messages it gives: This is Dockerfile:

FROM ubuntu:20.04

(yes, a humble beginning - or an extremly slimmed down repro)

docker build Dockerfile
[+] Building 0.0s (2/2) FINISHED
 => ERROR [internal] load build definition from Dockerfile                                                                                                                    0.0s
 => => transferring dockerfile: 33B                                                                                                                                           0.0s
 => ERROR [internal] load .dockerignore                                                                                                                                       0.0s
 => => transferring context: 33B                                                                                                                                              0.0s
------
 > [internal] load build definition from Dockerfile:
------
------
 > [internal] load .dockerignore:
------
failed to solve with frontend dockerfile.v0: failed to build LLB: error from sender: Dockerfile is not a directory

docker dockerfile

Solution 1:^[1]

You need to run docker build -f [docker_file_name] . (don't miss the dot at the end).

If the name of your file is Dockerfile then you don't need the -f and the filename.

Solution 2:^[2]

I faced a similar issue, I use the docker desktop for windows. Restarted the laptop and the issue was resolved. Hope it may help someone.

Solution 3:^[3]

For me, I had a Linux symlink in the same directory as the Dockerfile. When running docker build from Windows 10, it gave me the ERROR [internal] load build definition from Dockerfile. I suspect Docker docker build . scans the directory and, if it can't read one file, it crashes. For me, I mounted the directory with WSL and removed the symblink.

Solution 4:^[4]

I had the same issue but a different solution (on Windows):

I opened a console in my folder; my folder contains only Dockerfile
Dockerfile content was FROM ubuntu:20.04 (same as OP)
Ran docker build knowing that I had a Dockerfile in my current folder
I was getting the OP's same error message
I stopped the Docker Desktop service
Ran docker build again -- got "docker build" requires exactly 1 argument.
Ran docker build Dockerfile -- got unable to prepare context: context must be a directory: C:\z\docker\aem_ubuntu20\Dockerfile
Ran docker build . -- got error during connect: This error may indicate that the docker daemon is not running.
Re-started the Docker Desktop service
Ran docker build . -- success!
Conclusion: docker build PATH, where PATH must be a folder name and that folder must contain a Dockerfile

Solution 5:^[5]

In my case I got this error when running docker commands a wrong directory. Just cd to the dir where your Dockerfile is, and all is good again.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	upe
Solution 2	Shreekanth Gaanji
Solution 3	Guilherme Ferreira
Solution 4	rob_7cc
Solution 5	tishma

'Can you make any sense of Dockers error-messages?

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]