[Magento 2.2.5 - 2.3.x] Upload fails in image uploader

[mdesplenter]

Additional Triage information

• Issue was re-verified on the lates 2.3-develop (16 Oct 2019) for more details see [Magento 2.2.5 - 2.3.x] Upload fails in image uploader #16531 (comment)

Summary
When uploading an image in the uploader, the error "File validation failed." is shown. This error appeared after updating to 2.2.5.

Preconditions
PHP Version 7.0.1
Magento ver. 2.2.5
Make function "mime_content_type" undefined

Steps to reproduce

1. Edit a block
2. Select the image uploader ("Insert Image" button or the one in the editor)
3. Select an image from your hd and upload it.

Expected result
An added image in the gallery

Actual result
An error is shown: "File validation failed." No image is uploaded.

I tried different kind of filetypes. In 2.2.4 and previous versions there was no problem, the only thing that changed is the updated version.

[magento-engcom-team]

Hi @mdesplenter. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

@magento-engcom-team give me {$VERSION} instance

where {$VERSION} is version tags (starting from 2.2.0+) or develop branches (2.2-develop +).
For more details, please, review the Magento Contributor Assistant documentation.

@mdesplenter do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

[mdesplenter]

@magento-engcom-team give me 2.2.5 instance

[magento-engcom-team]

Hi @mdesplenter. Thank you for your request. I'm working on Magento 2.2.5 instance for you

[magento-engcom-team]

Hi @mdesplenter, here is your Magento instance.
Admin access: https://i-16531-2-2-5.engcom.dev.magento.com/admin
Login: admin Password: 123123q
Instance will be terminated in up to 3 hours.

[666triv]

im getting this error on the category section. On the content tab after selecting my image for the category i get the exact same error on an image that worked in 2.2.4

@mdesplenter, thank you for your report.
We were not able to reproduce this issue by following the steps you provided. Please provide more detailed steps to reproduce or try to reproduce this issue on a clean installation or latest release.

[666triv]

I tried uploading an image in the category section and it worked but this is a 2.2.6-dev instance. On 2.2.5 it gives the error. And this applies to any category you upload an image to.

@666triv we are testing on clean 2.2.5 installation and all goes well. So we need more detailed steps to reproduce.

[mdesplenter]

Does the validator need some database entries that might not been added in the upgrade from 2.2.4?
Tomorrow I'll try the 2.2.6-dev version, can I update this with composer?

[pieal86]

Same issue for me.
magento 2.2.5
I have used both nginx and apache.
PHP version 7.0
On Local env: nginx everything works fine..
On Server: Apache gives error "File validation Failed" when insert image in static blocks

@mdesplenter you can ask bot for new Magento instance and test on it.