Migration is busy with another operation

This means that somehow you have a given migration running twice - e.g., if you ran the migration in two windows at the same time. It could also mean that a migration had a fatal error causing it to exit without resetting the status from Importing to Idle - if that happens, you can use the migrate_tools command drush migrate-reset-status to reset it and try the migration again.

By "Migrate UI" you mean you're using the migrate_upgrade UI? What if you use the migrate-upgrade drush command? With the UI, if you check the log after migration completes is there anything else reported for these skipped migrations?

I'm just commenting on this issue to say that I ran into a similar situation, only my migration died somewhere in the middle due to other factors and I received the same error message in the end.

Executing drush migrate-reset-status d7_comment solved my issue. It's likely relevant to other users that migrate-rollback did not reset the status and comments were always skipped until I reset d7_comment's status. drush migrate-status was helpful in figuring this out.

Same problem in d6_user

drush migrate-upgrade ......
drush migrate-reset-status d6_user
Migration d6_user is already Idle [warning]

And run again:
drush migrate-upgrade ......

got error:
Upgrading d6_user
Passed variable is not an array or object, using empty array instead [error]

Any solution? Thanks.

I am trying to migrate from D7.43 to D8.1 using drush. I had the above listed failure "[some-module] is busy with another operation". I issued "drush clear-cache drush" and "drush migrate reset-status" with and without "d7_comment" at the end. I am still getting the initial failure (busy modules). Also, drush-migrate-reset-status gives the error "Migration ... does not exist [error]". NOTE the ... represents real extra space in the output message.

the migration eventually fails with a "call to undefined function field_read_field() in registration.module line 1286".

Any suggestions on proceeding would be GREATLY appreciated, considering I have now spent 3 full days trying to migrate my DB. I got it to partially work once before that, but something was corrupted so I started from scratch (deleted entire D8 db and ran the Drupal Installer) and now I can't get it ported at all.

I see this bug report is postponed. What additional information can I supply?
Windows 10 pro, Apache 2.4 64-bit, PHP 5.6 (now 7.0), MySql 5.6.

I've never been able to reproduce this problem, so there's not much I can do to track it down - it needs someone who can reproduce it to step through in a debugger and see what's going on. But, a red flag in your particular case:

the migration eventually fails with a "call to undefined function field_read_field() in registration.module line 1286".

Presumably registration.module is the Entity Registration module? field_read_field() does not exist in Drupal 8 - it looks like this module is not yet fully functional on Drupal 8, I would recommend uninstalling it for now.

Since the problem in the registration module is secondary to the "[module] is busy migrating" problem, I guess I'll have to wait until the "busy" problem is fixed before I can tackle the reg problem. Thanks for pointing me to the info on the development process for the reg module.

This means my port to D8 is definitely postponed.

Mikeryan said, "it needs someone who can reproduce it to step through in a debugger and see what's going on".
What can I do to trace the problem? What debugger is needed?

PhpStorm is the IDE and debugger of choice, these days - see https://www.drupaleasy.com/quicktips/debugging-phpstorm-including-drush for information on debugging Drupal using PhpStorm.

I guess I'll have to wait until the "busy" problem is fixed before I can tackle the reg problem

The module is entirely broken (calling at least one function that no longer exists in Drupal 8), and it's entirely possible it is a trigger your migration problems. I would strongly recommend you uninstall it until it's ready for D8.

The migrate process saves the status of each running migration in the database, any error in the code will abnormally terminate the process so the database won't be updated properly and will keep saying that "something is still running"

If you are totally sure that nothing else is running, use migrate-status to see the status, for example this is a normal output

 Group: XXX                                Status  Total  Imported  Unprocessed  Last imported
 XXXX                                                      Idle    199    0         6            2017-01-26 10:19:00
 Group:YYYY  Status  Total  Imported  Unprocessed  Last imported
 wp_vocabulary                                        Idle    4      0         4
 wp_terms                                                Idle    52     0         52
 wp_users                                                Idle    90     0         90
 wp_posts                                                Idle    821    0         821

If you see status importing, that is the one that is stucked

 Group: XXX               Status  Total  Imported  Unprocessed  Last imported
 XXXX                                         Importing    199    0         6            2017-01-26 10:19:00
 Group:YYYY  Status  Total  Imported  Unprocessed  Last imported
 wp_vocabulary                           Idle    4      0         4
 wp_terms                                   Idle    52     0         52
 wp_users                                    Idle    90     0         90
 wp_posts                                    Idle    821    0         821

Once you have identified what is running run migrate-reset-status with the name of the task.

drush migrate-reset-status XXXX

Fix your errors in the code and try again. If gets stuck again repeat the process and keep debugging.

Regards

This is reproducible by killing a migration process (control-C) while it is running. The fix in #19 works fine.

Changing from "closed (cannot reproduce)" to "fixed" in case other users are looking for the fix, as it is, in fact, reproducible.

#8 has solved the problem thanks @grahl!

I was getting this error for my Druapl 7 to Drupal 8 migration i.e

Migration upgrade_d7_node_type is busy with another operation: Importing

which was fixed with the following i.e

drush migrate-reset-status upgrade_d7_node_type

To summarise, by using 'drush migrate-reset-status ' will reset migration name to idle and after that try again and it should migrate without this error.

#19 and #23 works. Thanks for the resolution and the details too.

Yes i was getting this usse fro Drupal 7 to Drupal 8 migration of d7_user, #19 resolves the issue for me: drush migrate-reset-status d7_user