roachtest: activerecord failed

roachtest.activerecord [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21503676?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21503676?buildTab=artifacts#/activerecord) on release-25.4.17-rc @ [0447ee0a79bd81f5bcb15bcd613e6653dd0d1e0f](https://github.com/cockroachdb/cockroach/commits/0447ee0a79bd81f5bcb15bcd613e6653dd0d1e0f):

```
(orm_helpers.go:225).summarizeFailed:
Tests run on Cockroach v25.4.17-dev-0447ee0a79bd81f5bcb15bcd613e6653dd0d1e0f
Tests run against activerecord 8.1.0
182 Total Tests Run
176 tests passed
6 tests failed
2 tests skipped
1 test ignored
0 tests passed unexpectedly
6 tests failed unexpectedly
0 tests expected failed but skipped
1 test expected failed but not run
---
--- FAIL: SerializedAttributeTest#test_json_read_legacy_null (unexpected)
--- FAIL: SerializedAttributeTest#test_decorated_type_with_type_for_attribute (unexpected)
--- FAIL: SerializedAttributeTest#test_json_symbolize_names_returns_symbolized_names (unexpected)
--- FAIL: SerializedAttributeTest#test_serialized_json_attribute_returns_unserialized_value (unexpected)
--- FAIL: SerializedAttributeTest#test_serialized_attribute_calling_dup_method (unexpected)
--- FAIL: SerializedAttributeTest#test_decorated_type_with_decorator_block (unexpected)
For a full summary look at the activerecord artifacts
An updated blocklist (activeRecordBlocklist) is available in the artifacts' activerecord log
test artifacts and logs in: /artifacts/activerecord/cpu_arch=arm64/run_1
```

Parameters:
- arch=arm64
- cloud=gce
- coverageBuild=false
- cpu=4
- encrypted=false
- fs=ext4
- localSSD=false
- metamorphicLeases=default
- runtimeAssertionsBuild=false
- ssd=0
Help

See: [roachtest README](https://github.com/cockroachdb/cockroach/blob/master/pkg/cmd/roachtest/README.md)

See: [How To Investigate \(internal\)](https://cockroachlabs.atlassian.net/l/c/SSSBr8c7)

See: [Grafana](https://go.crdb.dev/roachtest-grafana/teamcity-21503676/activerecord/1788844278432/1788845071308)

Same failure on other branches

- #174371 roachtest: activerecord failed [C-test-failure O-roachtest O-robot P-2 T-sql-foundations branch-master]

/cc @cockroachlabs/sql-foundations

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*activerecord.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Start with the activerecord artifacts and log from the arm64 run, then inspect orm_helpers.go:225 and the six failing SerializedAttributeTest cases in ActiveRecord 8.1.0. Compare the failures with the activeRecordBlocklist and the related issue #174371. Done means identifying the compatibility failure and confirming the roachtest result after the appropriate test or blocklist change.

Written by the indexing model from the issue text.