Custom blocks cannot be properly exported and imported

Steps to reproduce

On Site A:

Create custom block

Assign this custom block to any region

Export configuration of the site

On Site B:

Import configuration from site A

Go to Block layout and you will see custom block in correctly assigned region, however block won't work or actually show anything.

Edit that block, you will see this messages:

Block description Broken/Missing This block is broken or missing. You may be missing content or you might need to enable the original module.

Go under Custom block library and you won't see custom block.

Block layout got exported but block content didn't resulting in broken relationship.

Comments & Activities

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It's likely this issue predates Contrib.social: some issue and comment data are missing.

Comment 12 months ago →
🇵🇱Poland azovsky
Looks like the Fixed Block Content module doesn't work anymore 💬 Module doesn't seem to do anything useful? Active .
Comment 9 months ago →
🇺🇸United States aarontocenter
I agree with @hoporr @tamerzg and @morsok above: this issue needs to be fixed here in core.

however @hoporr @jonathanshaw & @geerlingguy — yes it does render a site unusable the second you accidentally delete all blocks on production because of a config sync. Or worse yet doing a structural sync without importing everything, it will delete everything else.

@bdanin — clearly discusses why this is an issue, an issue open for more than 8 years, is the reason why many still bring this up. It has never been resolved, the addition of modules that make up for cores inability to get it right after 8x, 9x, and 10x, do we expect this to be resolved in 11x after 9 or 10 years of asking the same question? please help me understand how this is helpful to the community at large.

Steps to reproduce