REST API "The product can't be saved"

[Zyles]

Another case of bad error message feedback.

No logs other than the REST API giving terrible error message and a whole bunch of Googling has to be done.

In my case I tried to upload an image through the rest API using POST to /rest/V1/products/<sku>/media

The issue has to do with products having required fields that are not filled in. This could arise after changing attribute sets and not going back to fix it on old products for example.

The solution is to go into admin, filling in the required fields for the product, then trying to upload the image again.

Preconditions (*)

1. Magento 2.3.3

Steps to reproduce (*)

1. Have required fields on product that are not filled in
2. Try to upload image using REST API

Expected result (*)

1. Better error message that is actually helpful.
2. Log output in var/log

Actual result (*)

1. Terrible error message.
2. No logs
3. Not being able to upload the product image

[m2-assistant]

Hi @Zyles. Thank you for your report.
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• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

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

• yes
• no

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[m2-assistant]

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[engcom-Delta]

@Zyles , thank you for your report.
Looks like it would be good solution to add output with stack trace in var/log. For now response is "message": "The product can't be saved."
Marked as Future Request
cc @sdzhepa

[LiamKarlMitchell]

Related files.

vendor/magento/module-catalog/Model/Product/Gallery/GalleryManagement.php
79:            throw new StateException(__("The product can't be saved."));
129:            throw new StateException(__("The product can't be saved."));

vendor/magento/module-catalog/Test/Unit/Model/Product/Gallery/GalleryManagementTest.php
85:     * @expectedExceptionMessage The product can't be saved.
160:     * @expectedExceptionMessage The product can't be saved.

Change to include exception as 2nd argument to new StateException so that it is actually helpful.

 throw new StateException(__("The product can't be saved 1."), $e);

 throw new StateException(__("The product can't be saved 2."), $exception);

Also can throw for other reasons such as "The image MIME type is not valid or not supported." (Corrupted image or wrong extension/mimetype?)

[LiamKarlMitchell]

try {
            $product = $this->productRepository->save($product);
        } catch (InputException $inputException) {
            throw $inputException;
        } catch (\Exception $e) {
            throw new StateException(__('Cannot save product. [%1]', $e->getMessage()));
        }

Responds with

{
    "message": "Cannot save product. [%1]",
    "parameters": [
        "The image does not exist."
    ]
}

So then the client using the API has to put the parameters into the message.

Why "The image does not exist." I want to upload an image. (Magento 2.2.0)
The image is base64 encoded.

Another inner exception I got when I changed the filename was "Unable to save product"

In this case that I ran into,
When saving from Magento admin turns out permissions are denied on the cache folder...

Unable to write file into directory /var/www/html/pub/media/catalog/product/cache/7690288cef886e3600a2dbabc56d79c1/t/e. Access forbidden.

Ownership of the directory was wrong after migrating with rsyncing the folder to another server.

It does look like var/log/exception.log would have told me this if I had looked, so long as the critical/warning inner exceptions get logged I suppose that is fine, but the wording on the error could indicate a bit more as to why. E.g. "Permission error check exception log for more details."
main.CRITICAL: Warning: rename(/var/www/html/pub/media/tmp/catalog/product/T/1/Test-1.jpg): failed to open stream: Permission denied in /var/www/html/vendor/magento/framework/File/Uploader.php on line 283