@dmaza This is a good catch. Is this with $wgEnableMultiBlocks = false? When it is true, I find I can still press "Add block" to create a block. I think this is a side-effect of T389987.

In T392049#10746425, @dom_walden wrote:

@dmaza This is a good catch. Is this with $wgEnableMultiBlocks = false? When it is true, I find I can still press "Add block" to create a block. I think this is a side-effect of T389987.

Yes, this is only with $wgEnableMultiBlocks = false. I think it is related to the IP being considered "blocked" by the range. I don't think T389987 is causing this but I'll investigate

@dom_walden I checked on a random commit ( df3aae487aa ) before T389987 and it is still happening.

In T392049#10748088, @dmaza wrote:

@dom_walden I checked on a random commit ( df3aae487aa ) before T389987 and it is still happening.

My bad, pulled the wrong commit. This is indeed happening after T389987

Change #1137317 had a related patch set uploaded (by Dmaza; author: Dmaza):

[mediawiki/core@master] SpecialBlock [codex]: Fix add ip block when block range present

https://gerrit.wikimedia.org/r/1137317

Change #1137317 merged by jenkins-bot:

[mediawiki/core@master] SpecialBlock [codex]: Fix add ip block when block range present

https://gerrit.wikimedia.org/r/1137317

@dmaza You can still keep on adding IP range blocks even when $wgEnableMultiBlocks = false as seen in gif.

Test Result - Local

Status: ❌ AC1- You can still keep on adding ip range blocks
Environment: Local- MediaWiki: 1.44.0-alpha (4e09390) 17:02, 23 April 2025
OS: macOS Sequoia 15.3.2
Browser: Chrome 135
Device: MBA
Emulated Device: NA

Test Artifact(s):

Test Steps

Test Case 1: Ensure form is visible when blocking an IP within an existing blocked range with MultiBlocks disabled

1. Disable MultiBlocks ($wgEnableMultiBlocks = false) on the wiki.
2. Log in as an admin user with permission to block users.
3. Navigate to Special:Block.
4. Block the IP range '127.0.0.1/16'.
5. After the block is created, attempt to block the individual IP '127.0.0.20'.
6. ❌AC1: Confirm that the Special:Block form displays correctly and allows setting a new block on '127.0.0.20'.

✅IP Range Blockw/IP Block within Range- Yes Add Block	❌ Different IP range blocks not within same range- Yes Add Block	✅ IP Ranges blocks within each other- No Add Block

Test Case 2: Verify correct behavior when blocking an IP within an existing blocked range with MultiBlocks enabled

1. Enable MultiBlocks ($wgEnableMultiBlocks = true) on the wiki.
2. Log in as an admin user with permission to block users.
3. Navigate to Special:Block.
4. Block the IP range '127.0.0.1/16'.
5. After the block is created, attempt to block the individual IP '127.0.0.20'.
6. ✅ AC2: Confirm that the Special:Block form displays correctly, allowing the admin to create an overlapping block on '127.0.0.20' without errors.

Change #1140554 had a related patch set uploaded (by Dmaza; author: Dmaza):

[mediawiki/core@master] Fix incorrect form display when multiblocks disabled for IP/IP Ranges

https://gerrit.wikimedia.org/r/1140554

Change #1140554 merged by jenkins-bot:

[mediawiki/core@master] Fix incorrect form display when multiblocks disabled for IP/IP Ranges

https://gerrit.wikimedia.org/r/1140554

In T392049#10777595, @GMikesell-WMF wrote:

@dmaza You can still keep on adding IP range blocks even when $wgEnableMultiBlocks = false as seen in gif.

Everything looks good as far as I can tell. Feel free to resolve and close this task