[Docs] Release notes (#99)

* [Docs] Release notes

* [Docs] Migration Guide

* [Docs] fixing links

* [Docs] fixing links

* [Docs] fixing links

Author: fashxp

doc/02_Pimcore_Platform/04_Platform_Versions/README.md

@@ -46,7 +46,7 @@ import VersionTimeline from '@site/src/components/VersionTimeline';
 
 | Version | Release Notes | Module Details | LTS | LTS Support Until |
 |---------|--------------|----------------|:---:|-------------------|
-| 2026.1  | [Release Notes](../05_Updating_Pimcore/02_Release_Notes/01_2026.1.md) | [Details](01_2026.1.md) | | |
+| 2026.1  | [Release Notes](../05_Updating_Pimcore/02_Release_Notes/01_2026.1/README.md) | [Details](01_2026.1.md) | | |
 | 2025.4  | [Release Notes](../05_Updating_Pimcore/02_Release_Notes/02_2025.4.md) | [Details](02_2025.4.md) | ✅ | December 2028 |
 | 2025.3  | [Release Notes](../05_Updating_Pimcore/02_Release_Notes/03_2025.3.md) | [Details](03_2025.3.md) | | |
 | 2025.2  | [Release Notes](../05_Updating_Pimcore/02_Release_Notes/04_2025.2.md) | [Details](04_2025.2.md) | | |

doc/02_Pimcore_Platform/05_Updating_Pimcore/02_Release_Notes/01_2026.1.md

@@ -0,0 +1,241 @@
+# Migration Guide: Pimcore 2026.1
+
+This guide walks through the steps required to migrate an existing Pimcore installation to Platform Version
+2026.1. It covers the 2026.1-specific tasks in the sequence they must be performed.
+
+For the general major version upgrade process and background on each phase, see
+[Major Version Upgrades](../../03_Major_Version_Upgrades.md).
+
+## Migration Steps
+
+### 1. Update to the Latest 2025.4 Release
+
+Start from the latest available bugfix release of 2025.4. This ensures all deprecation notices and
+preparatory changes from the 2025 cycle are in place.
+
+```bash
+composer require pimcore/platform-version:"^2025.4" --no-update
+COMPOSER_MEMORY_LIMIT=-1 composer update
+bin/console doctrine:migrations:migrate
+```
+
+### 2. Install Pimcore Studio (if not already done)
+
+2026.1 removes Admin UI Classic entirely. Pimcore Studio must be installed and fully functional before you
+upgrade. If Studio is already active in your installation, verify it works correctly and skip to Step 3.
+See the [Studio UI installation guide](../../../../03_Getting_Started/01_Installation/03_Advanced_Installation_Topics/02_Pimcore_Studio_Setup.md)
+for the full setup guide.
+
+After installation, log into Pimcore Studio and verify it works correctly on 2025.4 before proceeding.
+
+### 3. Resolve All Deprecations
+
+Check for deprecation notices before upgrading:
+
+- **Symfony deprecation log** - `var/log/dev.deprecations.log` or the profiler toolbar in dev mode
+- **Code** - search for `@deprecated` usages in your codebase and custom bundles
+- **Pimcore Studio** - some deprecations surface as warnings in the UI
+
+Resolve everything you can. For deprecations that depend on third-party bundles, verify those bundles have a
+compatible release for 2026.1 before proceeding.
+
+### 4. Back Up
+
+Create a full backup of your database and project files. If the upgrade fails, restore the backup, revert
+`composer.lock`, and run `composer install` to return to the previous state.
+
+### 5. Remove Deprecated Bundles from composer.json
+
+The following bundles are removed in 2026.1. Remove them from `composer.json` and clean up any related
+service configuration, event listeners, and references in your code. Do not run `composer update` yet -
+that happens in Step 9.
+
+Functionality now part of Pimcore Studio:
+- `pimcore/advanced-object-search-bundle`
+- `pimcore/perspective-editor`
+- `pimcore/simple-backend-search-bundle`
+
+Discontinued:
+- `pimcore/file-explorer-bundle`
+- `pimcore/glossary-bundle`
+- `pimcore/google-marketing-bundle`
+- `pimcore/newsletter-bundle`
+- `pimcore/seo-bundle` (redirects, robots.txt, and sitemaps remain in the core)
+- `pimcore/static-routes-bundle`
+- `pimcore/system-info-bundle`
+- `pimcore/word-export-bundle`
+- `pimcore/output-data-config-toolkit`
+- `pimcore/web2print-tools`
+
+### 6. Update PHP and Symfony Version Constraints
+
+PHP 8.3 and Symfony 6.x support have been removed.
+
+- Ensure your server runs **PHP 8.4 or 8.5**
+- Remove any explicit Symfony 6.x version constraints from `composer.json`
+
+Do not run `composer update` yet. The update to Symfony 7.x happens as part of Step 9.
+
+### 7. Migrate Email Log Folder Structure
+
+The folder structure for email logs has changed to `YYYY/MM/DD/<filename>`. Run this migration against your
+current 2025.4 installation before upgrading:
+
+```bash
+bin/console pimcore:migrate:mail-logs-folder-structure
+```
+
+Alternatively, move the existing log files manually into the new directory structure.
+
+### 8. Fix Database Collation
+
+2026.1 explicitly sets `utf8mb4_unicode_520_ci` on all `utf8mb4` tables and columns. Previous versions did
+not specify a collation, so MySQL/MariaDB applied its own default (`utf8mb4_general_ci` on MySQL 5.7/MariaDB,
+`utf8mb4_0900_ai_ci` on MySQL 8). The mismatch can cause foreign key constraint errors during the migrations
+in Step 11.
+
+This is **not** handled by the standard Doctrine migration - run it manually before upgrading.
+
+**1. Generate ALTER TABLE statements.** Run the query below to produce the statements for all affected
+tables. Copy the output.
+
+```sql
+SELECT CONCAT(
+  'ALTER TABLE `', TABLE_NAME,
+  '` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci;'
+)
+FROM INFORMATION_SCHEMA.TABLES
+WHERE TABLE_SCHEMA = 'your_database_name'
+  AND TABLE_TYPE = 'BASE TABLE'
+  AND TABLE_COLLATION IN ('utf8mb4_general_ci', 'utf8mb4_0900_ai_ci')
+ORDER BY TABLE_NAME;
+```
+
+**2. Safety check.** Before executing, verify that no `utf8mb4_bin` columns (used for case-sensitive
+keys and JSON data) appear in the results. Those must not be changed.
+
+```sql
+SELECT TABLE_NAME, COLUMN_NAME, COLUMN_TYPE, COLLATION_NAME
+FROM INFORMATION_SCHEMA.COLUMNS
+WHERE TABLE_SCHEMA = 'your_database_name'
+  AND COLLATION_NAME IN ('utf8mb4_general_ci', 'utf8mb4_0900_ai_ci')
+ORDER BY TABLE_NAME, COLUMN_NAME;
+```
+
+**3. Execute.** Run the `ALTER TABLE` statements generated above against your database.
+
+### 9. Update to 2026.1
+
+```bash
+composer require pimcore/platform-version:"^2026.1" --no-update
+COMPOSER_MEMORY_LIMIT=-1 composer update
+```
+
+Do not run migrations yet.
+
+### 10. Apply Code Changes
+
+Apply the following breaking changes to your codebase:
+
+- Remove any remaining references to removed bundles or Admin Classic interfaces
+  (`PimcoreBundleAdminClassicInterface`, `BundleAdminClassicTrait`, `AdminSubscriber`, etc.)
+- Update the Messenger transport DSN: rename `PIMCORE_MESSENGER_TRANSPORT_DSN` to
+  `PIMCORE_MESSENGER_TRANSPORT_DSN_PREFIX` and add a trailing separator
+  (e.g. `doctrine://default` becomes `doctrine://default?queue_name=`).
+  This affects both your `.env` files and any deployment configuration (secrets managers, Kubernetes, etc.)
+  where this variable is set.
+- Update OpenSearch/Elasticsearch configuration from the `hosts` array YAML format to the DSN env var format
+  (`PIMCORE_OPENSEARCH_DSN` or `PIMCORE_ELASTICSEARCH_DSN`)
+- If you use the Pimcore installer in CI/CD pipelines, update from `bin/console pimcore:install` to
+  `vendor/bin/pimcore-install --install-profile=<YourProfileClass>`
+
+Review the [Core Framework upgrade notes](https://github.com/pimcore/pimcore/blob/2026.1/doc/13_Upgrade_Notes/README.md#pimcore-202610)
+and the upgrade notes of each bundle you use (see [All Bundle Upgrade Notes](README.md#upgrade-notes)).
+
+Clear the Symfony container cache after applying changes:
+
+```bash
+bin/console cache:clear
+```
+
+### 11. Run Migrations
+
+```bash
+bin/console doctrine:migrations:migrate
+```
+
+### 12. Rebuild Class Definitions
+
+After migrations, rebuild the object class definitions to ensure all generated PHP classes reflect the
+current state:
+
+```bash
+bin/console pimcore:deployment:classes-rebuild
+```
+
+### 13. Clear Application Caches
+
+```bash
+bin/console pimcore:cache:clear
+```
+
+### 14. Test
+
+- Log into Pimcore Studio and verify data objects, assets, and documents load and save correctly
+- Run your automated test suite
+- Verify custom bundles, integrations, and event listeners
+- Check functionality related to resolved deprecations
+
+## Post-Upgrade Manual Work
+
+The following cannot be handled by Composer or migrations. Plan time for these after the upgrade is complete.
+
+### Perspectives and Custom Views
+
+From a functional standpoint, perspectives and custom views serve the same purpose in Pimcore Studio as in
+the Classic UI. The technical implementation is entirely different, however. Existing perspectives and custom
+views cannot be imported or automatically converted - they must be recreated in Pimcore Studio.
+
+### Dashboards
+
+Dashboards created in the Classic UI are not compatible with Pimcore Studio and must be recreated. Reports
+used within dashboards are unaffected and continue to work without migration.
+
+### Custom Grid Configurations
+
+The technical implementation of grid configurations has changed completely. All existing custom grid
+configurations must be rebuilt in Pimcore Studio - including globally defined configurations and user-level
+configurations. Custom grid operators must also be reviewed and updated for compatibility with the new
+grid architecture.
+
+### Datahub Configuration Schema Migration
+
+Datahub File Export, Datahub Productsup, Datahub Simple REST, and Datahub Webhooks have moved from a
+tree-based schema definition to a pipeline-based architecture. Existing configurations continue to execute
+without changes. However, a configuration must be fully migrated to the new format before it can be edited
+in Pimcore Studio. Migration is done through the Pimcore Studio UI.
+
+Read-only support for the legacy tree-based schema definition will be removed in 2027.1.0.
+See the [Release Notes](README.md#datahub-configuration-schema-changes) and the upgrade notes of the
+affected bundles for details.
+
+### Custom Bundles and Backend Extensions
+
+Custom bundles, event listeners, service definitions, and integrations must all be reviewed. Pay particular
+attention to:
+
+- Admin Classic UI extensions, plugins, and custom controllers - removed, must be reimplemented for
+  Pimcore Studio if still needed
+- Custom grid operators - review for compatibility with the new pipeline-based grid architecture
+- Event listeners referencing removed classes (`AdminSubscriber`,
+  `PimcoreBundleAdminClassicInterface`, etc.)
+- Any code that depends on the removed bundles listed in Step 5
+
+Test all custom functionality in a staging environment before going live.
+
+## Further Resources
+
+- [Release Notes for 2026.1](README.md)
+- [Major Version Upgrades](../../03_Major_Version_Upgrades.md)
+- [Core Framework Upgrade Notes](https://github.com/pimcore/pimcore/blob/2026.1/doc/13_Upgrade_Notes/README.md#pimcore-202610)
+- [All Bundle Upgrade Notes](README.md#upgrade-notes)