Since users have voiced their concerns about manually editing the database I have created a bash script that does it for you.
Please follow these steps if you have this issue:

1. create an app backup of your @vaultwarden Cloudron app
2. put the erroring @vaultwarden app in recovery mode
3. open the File Manager of your @vaultwarden app and create a fix_db.sh file
4. copy and paste the following script into the just created fix_db.sh file:

   #!/bin/bash
   
   echo "=> Checking if DEFAULT_CHARACTER_SET_NAME and DEFAULT_COLLATION_NAME are set to utf8mb4 and utf8mb4_unicode_ci"
   
   CURRENT_DEFAULT_CHARACTER_SET_NAME=$(mysql --silent --skip-column-names --user=${CLOUDRON_MYSQL_USERNAME} --password=${CLOUDRON_MYSQL_PASSWORD} --host=${CLOUDRON_MYSQL_HOST} ${CLOUDRON_MYSQL_DATABASE} -e "SELECT DEFAULT_CHARACTER_SET_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = '${CLOUDRON_MYSQL_DATABASE}';" 2>/dev/null)
   CURRENT_DEFAULT_COLLATION_NAME=$(mysql --silent --skip-column-names --user=${CLOUDRON_MYSQL_USERNAME} --password=${CLOUDRON_MYSQL_PASSWORD} --host=${CLOUDRON_MYSQL_HOST} ${CLOUDRON_MYSQL_DATABASE} -e "SELECT DEFAULT_COLLATION_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = '${CLOUDRON_MYSQL_DATABASE}';" 2>/dev/null)
   FIX_NEEDED=0
   
   if [ "${CURRENT_DEFAULT_CHARACTER_SET_NAME}" != "utf8mb4" ] || [ "${CURRENT_DEFAULT_COLLATION_NAME}" != "utf8mb4_unicode_ci" ]; then
       echo "=> DEFAULT_CHARACTER_SET_NAME or DEFAULT_COLLATION_NAME is not set to utf8mb4 or utf8mb4_unicode_ci."
       echo "==> Current values are: DEFAULT_CHARACTER_SET_NAME=${CURRENT_DEFAULT_CHARACTER_SET_NAME}, DEFAULT_COLLATION_NAME=${CURRENT_DEFAULT_COLLATION_NAME}"
       FIX_NEEDED=1
   else
       echo "=> DEFAULT_CHARACTER_SET_NAME is ${CURRENT_DEFAULT_CHARACTER_SET_NAME} and DEFAULT_COLLATION_NAME is ${CURRENT_DEFAULT_COLLATION_NAME}"
       echo "=> Nothing to do - quitting."
       FIX_NEEDED=0
       exit 0
   fi
   
   if [ ${FIX_NEEDED} -eq 1 ]; then
       read -p "Have you created a backup of your Cloudron Vaultwarden app? (y/N): " yn
       case $yn in
           [Yy]* )
               echo "=> Setting database character set and collation to utf8mb4 and utf8mb4_unicode_ci."
               mysql --user=${CLOUDRON_MYSQL_USERNAME} --password=${CLOUDRON_MYSQL_PASSWORD} --host=${CLOUDRON_MYSQL_HOST} ${CLOUDRON_MYSQL_DATABASE} -e "ALTER DATABASE \`${CLOUDRON_MYSQL_DATABASE}\` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;" 2>/dev/null
               echo "=> Converting all tables to character set utf8mb4 and collation utf8mb4_unicode_ci."
               mysql --silent --skip-column-names \
     --user="${CLOUDRON_MYSQL_USERNAME}" \
     --password="${CLOUDRON_MYSQL_PASSWORD}" \
     --host="${CLOUDRON_MYSQL_HOST}" \
     "${CLOUDRON_MYSQL_DATABASE}" \
     -e "SELECT CONCAT('ALTER TABLE \`', TABLE_NAME,'\` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;') AS CharSetConvert FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='${CLOUDRON_MYSQL_DATABASE}' AND TABLE_TYPE=\"BASE TABLE\";" 2>/dev/null | while read -r sql_command; do
                   echo "==> Executing: ${sql_command}"
                   mysql --user=${CLOUDRON_MYSQL_USERNAME} --password=${CLOUDRON_MYSQL_PASSWORD} --host=${CLOUDRON_MYSQL_HOST} ${CLOUDRON_MYSQL_DATABASE} -e "SET foreign_key_checks=0; ${sql_command} SET foreign_key_checks=1;" 2>/dev/null
               done
               ;;
           [Nn]* )
               echo "=> Please create a backup of your database before proceeding with the fix. Exiting."
               exit 1
               ;;
           * )
               echo "=> Invalid response. Please answer with y or n. Exiting."
               exit 1
               ;;
       esac
   fi
   

5. open the Web Terminal of your @vaultwarden Cloudron app
6. execute the following command:

   bash /app/data/fix_db.sh
   

7. Execute the following command to start @vaultwarden:

   /app/pkg/start.sh
   

8. Validate if your @vaultwarden is now working correctly
9. If validated working, you can delete the fix_db.sh file and disable the recovery mode of your @vaultwarden Cloudron app

Note:
If there are issues with the copy and paste from Windows devices apperent by error messages like line 2: $'\r': command not found, please run the following command to fix the script:

sed -i 's/\r$//g' /app/data/fix_db.sh

If you run into any issues, copy the output of the terminal, post it here and restore your app from the backup created.

@james said:

Please follow these steps if you have this issue:

Can this script be run on the working version I reverted to, or do I need to update to the broken version and then run it?

Edit: yes, it seems fixing the db and then updating also works fine.

If possible, give the solution I linked also an upvote to improve the forum search.

I have also merged this topic into the original topic so there is no duplicate.

thanks a lot

In the web terminal, first get the database name:

echo $CLOUDRON_MYSQL_DATABASE

Then, click the mysql button above and press enter. Replace DB_NAME_HERE . You should get utf8mb4

mysql> SELECT   SCHEMA_NAME,   DEFAULT_CHARACTER_SET_NAME,   DEFAULT_COLLATION_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = 'DB_NAME_HERE';
+------------------+----------------------------+------------------------+
| SCHEMA_NAME      | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME |
+------------------+----------------------------+------------------------+
| fb30d5a9f5fd3620 | utf8mb4                    | utf8mb4_unicode_ci     |
+------------------+----------------------------+------------------------+

Then, check all the tables.

mysql> SELECT   TABLE_NAME,   TABLE_TYPE,   ENGINE,   TABLE_COLLATION FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'fb30d5a9f5fd3620' ORDER BY TABLE_NAME;
+----------------------------+------------+--------+--------------------+
| TABLE_NAME                 | TABLE_TYPE | ENGINE | TABLE_COLLATION    |
+----------------------------+------------+--------+--------------------+
| __diesel_schema_migrations | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| archives                   | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| attachments                | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| auth_requests              | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| ciphers                    | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| ciphers_collections        | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| collections                | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| collections_groups         | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| devices                    | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| emergency_access           | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| event                      | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| favorites                  | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| folders                    | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| folders_ciphers            | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| groups                     | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| groups_users               | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| invitations                | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| org_policies               | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| organization_api_key       | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| organizations              | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| sends                      | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| sso_auth                   | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| sso_users                  | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| twofactor                  | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| twofactor_duo_ctx          | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| twofactor_incomplete       | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| users                      | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| users_collections          | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
| users_organizations        | BASE TABLE | InnoDB | utf8mb4_unicode_ci |
+----------------------------+------------+--------+--------------------+
29 rows in set (0.01 sec)

If the table encoding is not the above, then first take a backup of the app and then follow the instructions at https://github.com/dani-garcia/vaultwarden/wiki/Using-the-MariaDB-(MySQL)-Backend#foreign-key-errors-collation-and-charset

Reverting to previous version restore functionalities/access indeed.

May 05 20:47:32 => Exporting env vars expected by Vaultwarden
May 05 20:47:32 => Starting Bitwarden
May 05 20:47:32 /--------------------------------------------------------------------\
May 05 20:47:32 |                        Starting Vaultwarden                        |
May 05 20:47:32 |--------------------------------------------------------------------|
May 05 20:47:32 | This is an *unofficial* Bitwarden implementation, DO NOT use the   |
May 05 20:47:32 | official channels to report bugs/features, regardless of client.   |
May 05 20:47:32 | Send usage/configuration questions or feature requests to:         |
May 05 20:47:32 |   https://github.com/dani-garcia/vaultwarden/discussions or        |
May 05 20:47:32 |   https://vaultwarden.discourse.group/                             |
May 05 20:47:32 | Report suspected bugs/issues in the software itself at:            |
May 05 20:47:32 |   https://github.com/dani-garcia/vaultwarden/issues/new            |
May 05 20:47:32 \--------------------------------------------------------------------/
May 05 20:47:32 2026-05-06T03:47:32Z 
May 05 20:47:32 [INFO] Using saved config from `/app/data/config.json` for configuration.
May 05 20:47:32 2026-05-06T03:47:32Z 
May 05 20:47:32 [2026-05-06 03:47:32.167][panic][ERROR] thread 'main' panicked at 'Error running migrations: QueryError(DieselMigrationName { name: "2026-03-09-005927_add_archives", version: MigrationVersion("20260309005927") }, DatabaseError(Unknown, "Referencing column 'user_uuid' and referenced column 'uuid' in foreign key constraint 'archives_ibfk_1' are incompatible."))': src/db/mod.rs:501
May 05 20:47:32 0: vaultwarden::init_logging::{{closure}}
May 05 20:47:32 1: std::panicking::panic_with_hook
May 05 20:47:32 2: std::panicking::panic_handler::{closure#0}
May 05 20:47:32 3: std::sys::backtrace::__rust_end_short_backtrace::<std::panicking::panic_handler::{closure#0}, !>
May 05 20:47:32 4: __rustc::rust_begin_unwind
May 05 20:47:32 5: core::panicking::panic_fmt
May 05 20:47:32 6: core::result::unwrap_failed
May 05 20:47:32 7: vaultwarden::db::DbPool::from_config
May 05 20:47:32 8: vaultwarden::main::{{closure}}
May 05 20:47:32 9: vaultwarden::main
May 05 20:47:32 10: std::sys::backtrace::__rust_begin_short_backtrace
May 05 20:47:32 11: main
May 05 20:47:32 12: <unknown>
May 05 20:47:32 13: __libc_start_main
May 05 20:47:32 14: _start

Any ideas on this one?

This issue has been adressed and a fix is avaiable here: https://forum.cloudron.io/post/117779
I will merge this topic into the existing one.

 Please generate a secure Argon2 PHC string by using `vaultwarden hash` or `argon2`.
Jan 17 19:10:33 See: https://github.com/dani-garcia/vaultwarden/wiki/Enabling-admin-page#secure-the-admin_token
Jan 17 19:10:33 2026-01-17T19:10:33+01:00
Jan 17 19:10:34 [2026-01-17 18:10:34.083][panic][ERROR] thread 'main' panicked at 'Error running migrations: QueryError(DieselMigrationName { name: "2024-03-06-170000_add_sso_users", version: MigrationVersion("20240306170000") }, DatabaseError(Unknown, "Referencing column 'user_uuid' and referenced column 'uuid' in foreign key constraint 'sso_users_ibfk_1' are incompatible."))': src/db/mod.rs:505
Jan 17 19:10:34 0: vaultwarden::init_logging::{{closure}}
Jan 17 19:10:34 1: std::panicking::panic_with_hook
Jan 17 19:10:34 2: std::panicking::panic_handler::{{closure}}
Jan 17 19:10:34 3: std::sys::backtrace::__rust_end_short_backtrace
Jan 17 19:10:34 4: __rustc::rust_begin_unwind
Jan 17 19:10:34 5: core::panicking::panic_fmt
Jan 17 19:10:34 6: core::result::unwrap_failed
Jan 17 19:10:34 7: vaultwarden::db::DbPool::from_config
Jan 17 19:10:34 8: vaultwarden::main::{{closure}}
Jan 17 19:10:34 9: vaultwarden::main
Jan 17 19:10:34 10: std::sys::backtrace::__rust_begin_short_backtrace
Jan 17 19:10:34 11: main
Jan 17 19:10:34 12: <unknown>
Jan 17 19:10:34 13: __libc_start_main
Jan 17 19:10:34 14: _start
Jan 17 19:10:34 2026-01-17T19:10:34+01:00

Can you help me ?

Regards

Did you change the notification setting in this topic (top right bell icon)?

PS: i didn't receive any email notification of the mentions.