panic: recovered from errgroup.Group: assignment to entry in nil map

[martinjagodic]

I get the error in the title with the latest release. It's reported already in #13810, a fix was merged, but it seems it's not fixing the problem. This does not happen on all projects, but I can't identify the reason.

entire log

hugo
Start building sites … 
hugo v0.148.0+extended+withdeploy darwin/arm64 BuildDate=2025-07-08T13:34:49Z VendorInfo=brew

Total in 137 ms
panic: recovered from errgroup.Group: recovered from errgroup.Group: assignment to entry in nil map
        goroutine 25 [running]:
        runtime/debug.Stack()
                runtime/debug/stack.go:26 +0x64
        golang.org/x/sync/errgroup.(*Group).add.func1.1()
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:117 +0x220
        panic({0x1071acb40?, 0x10946a190?})
                runtime/panic.go:792 +0x124
        github.com/gohugoio/hugo/hugolib.(*pageState).setMetaPost.func1(...)
                github.com/gohugoio/hugo/hugolib/page__meta.go:313
        github.com/gohugoio/hugo/common/maps.(*Ordered[...]).Range(...)
                github.com/gohugoio/hugo/common/maps/ordered.go:132
        github.com/gohugoio/hugo/hugolib.(*pageState).setMetaPost(0x14000edd320, 0x1400169a4a0)
                github.com/gohugoio/hugo/hugolib/page__meta.go:305 +0xf78
        github.com/gohugoio/hugo/hugolib.(*sitePagesAssembler).applyAggregates.func1({0x140019c6d70, 0x39}, {0x107755e20, 0x14000edd320}, 0x78?)
                github.com/gohugoio/hugo/hugolib/content_map_page.go:1446 +0x3a0
        github.com/gohugoio/hugo/hugolib/doctree.(*NodeShiftTreeWalker[...]).Walk.func1({0x1073f5360, 0x14001d6e678})
                github.com/gohugoio/hugo/hugolib/doctree/nodeshifttree.go:377 +0x108
        github.com/armon/go-radix.recursiveWalk(0x14002251bf0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:523 +0x48
        github.com/armon/go-radix.recursiveWalk(0x14002251bc0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140020479e0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140020476b0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140020e7020, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x14001c12390, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140022504b0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x14002250480, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140019017a0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x14001f6bd40, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x140017083f0, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.recursiveWalk(0x1400028a660, 0x14001125da0)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:532 +0xa0
        github.com/armon/go-radix.(*Tree).Walk(...)
                github.com/armon/go-radix@v1.0.1-0.20221118154546-54df44f2176c/radix.go:453
        github.com/gohugoio/hugo/hugolib/doctree.(*NodeShiftTreeWalker[...]).Walk(0x107762f80?, {0x3?, 0x140004772e8?})
                github.com/gohugoio/hugo/hugolib/doctree/nodeshifttree.go:387 +0xf0
        github.com/gohugoio/hugo/hugolib.(*sitePagesAssembler).applyAggregates(0x14000429480)
                github.com/gohugoio/hugo/hugolib/content_map_page.go:1523 +0x230
        github.com/gohugoio/hugo/hugolib.(*sitePagesAssembler).assemblePagesStep1(0x14000429480, {0x140000b4700?, 0x0?})
                github.com/gohugoio/hugo/hugolib/content_map_page.go:1867 +0x44
        github.com/gohugoio/hugo/hugolib.(*HugoSites).assemble.func1()
                github.com/gohugoio/hugo/hugolib/hugo_sites_build.go:304 +0x28
        github.com/gohugoio/hugo/common/para.(*errGroupRunner).Run.func1()
                github.com/gohugoio/hugo/common/para/para.go:52 +0x2c
        golang.org/x/sync/errgroup.(*Group).add.func1()
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:128 +0x88
        created by golang.org/x/sync/errgroup.(*Group).add in goroutine 23
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:96 +0x80

        goroutine 23 [running]:
        runtime/debug.Stack()
                runtime/debug/stack.go:26 +0x64
        golang.org/x/sync/errgroup.(*Group).add.func1.1()
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:117 +0x220
        panic({0x107459de0?, 0x14001609b90?})
                runtime/panic.go:792 +0x124
        golang.org/x/sync/errgroup.(*Group).Wait(0x140012bfe60)
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:70 +0x7c
        github.com/gohugoio/hugo/hugolib.(*HugoSites).assemble(0x140007a4c60, {0x10774c968, 0x1095717c0}, {0x107759eb0?, 0x140001191a0?}, 0x140014e8bc0)
                github.com/gohugoio/hugo/hugolib/hugo_sites_build.go:307 +0x338
        github.com/gohugoio/hugo/hugolib.(*HugoSites).Build.func4(...)
                github.com/gohugoio/hugo/hugolib/hugo_sites_build.go:152
        github.com/gohugoio/hugo/hugolib.(*HugoSites).Build(0x140007a4c60, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, {0x0, ...})
                github.com/gohugoio/hugo/hugolib/hugo_sites_build.go:159 +0x58c
        github.com/gohugoio/hugo/commands.(*hugoBuilder).buildSites(0x0?, 0x0)
                github.com/gohugoio/hugo/commands/hugobuilder.go:425 +0xcc
        github.com/gohugoio/hugo/commands.(*hugoBuilder).fullBuild.func3()
                github.com/gohugoio/hugo/commands/hugobuilder.go:542 +0x24
        golang.org/x/sync/errgroup.(*Group).add.func1()
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:128 +0x88
        created by golang.org/x/sync/errgroup.(*Group).add in goroutine 1
                golang.org/x/sync@v0.15.0/errgroup/errgroup.go:96 +0x80


goroutine 1 [running]:
golang.org/x/sync/errgroup.(*Group).Wait(0x14000118fc0)
        golang.org/x/sync@v0.15.0/errgroup/errgroup.go:70 +0x7c
github.com/gohugoio/hugo/commands.(*hugoBuilder).fullBuild(0x14000a01980, 0x0)
        github.com/gohugoio/hugo/commands/hugobuilder.go:564 +0x288
github.com/gohugoio/hugo/commands.(*hugoBuilder).build(0x14000a01980)
        github.com/gohugoio/hugo/commands/hugobuilder.go:397 +0x5c
github.com/gohugoio/hugo/commands.(*rootCommand).Run.func1(0x14000a01980?, 0x14000146380?)
        github.com/gohugoio/hugo/commands/commandeer.go:382 +0x78
github.com/gohugoio/hugo/commands.(*rootCommand).Run(0x14000a36000, {0x0?, 0x0?}, 0x14000146380, {0x0?, 0x4b63c922e655ddbc?, 0x14000a9d9f0?})
        github.com/gohugoio/hugo/commands/commandeer.go:387 +0xf8
github.com/bep/simplecobra.(*Commandeer).compile.func1(0x14000a3c100?, {0x1095717c0?, 0x4?, 0x106614d71?})
        github.com/bep/simplecobra@v0.6.0/simplecobra.go:113 +0x54
github.com/spf13/cobra.(*Command).execute(0x14000a38008, {0x140001ac0c0, 0x0, 0x0})
        github.com/spf13/cobra@v1.9.1/command.go:1015 +0x844
github.com/spf13/cobra.(*Command).ExecuteC(0x14000a38008)
        github.com/spf13/cobra@v1.9.1/command.go:1148 +0x384
github.com/spf13/cobra.(*Command).ExecuteContextC(...)
        github.com/spf13/cobra@v1.9.1/command.go:1080
github.com/bep/simplecobra.(*Exec).Execute(0x14000a0a220, {0x10774c968?, 0x1095717c0?}, {0x140001ac0c0?, 0x140000b4678?, 0x10432eee4?})
        github.com/bep/simplecobra@v0.6.0/simplecobra.go:155 +0xb4
github.com/gohugoio/hugo/commands.Execute({0x140001ac0c0, 0x0, 0x0})
        github.com/gohugoio/hugo/commands/commandeer.go:68 +0x27c
main.main()
        github.com/gohugoio/hugo/main.go:25 +0x70

What version of Hugo are you using (hugo version)?

$ hugo version
hugo v0.148.0+extended+withdeploy darwin/arm64 BuildDate=2025-07-08T13:34:49Z VendorInfo=brew

Does this issue reproduce with the latest release?

yes

[manusaurio]

Not sure if it's still relevant, seeing #13854. But I was able to reproduce the error in a brand new project.

1. hugo new site hugomre
2. cd hugomre
3. mkdir content/test/
4. Create _index.md in the new directory:

---
title: Test
cascade:
- build:
    list: local
  target:
    path: '{/test/**}'
- params:
    title: 'Test page'
  target:
    path: '{/test/**}'
---

5. hugo

In this case Hugo crashes if the targets in - build and - params share the same value ('{/test/**}')

hugo version: hugo v0.148.0+extended+withdeploy linux/amd64 BuildDate=unknown

[bep]

@manusaurio thanks, I'll add that case as a test to the PR in question. I will push a bug release of Hugo later today.

[github-actions]

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