Azure Storage Action: can't use parenthesis or exclamation mark on blob name match predicate

Question

Azure Storage Action: can't use parenthesis or exclamation mark on blob name match predicate

Thomas Bolon 1

I try to modify any file where the name matches the pattern "((DEL!(???)))".

I can't save the action when this condition is set, I receive validation errors.

I tried escaping the characters without success.

It seems that a lot of special characters are not supported. If that's the case, the documentation should be updated, as it's currently stopping a lot of usage. In our current situation we can't get rid of these special characters because the pattern will be too broad if we remove them.

Vallepu Venkateswarlu 10,590 Reputation points Microsoft External Staff Moderator

2026-06-16T14:44:07.2766667+00:00
Hi Thomas Bolon,

Welcome to Microsoft Q&A Platform.

I see what you’re running into. You’re trying to use a blob name match predicate containing special characters like parentheses ( ) and exclamation mark ! inside a pattern such as ((DEL!(???))), but Azure Storage validates the action and rejects it.

Based on the provided (but not actually included) documentation reference, it sounds like the key issue is that blob name match predicates have parsing/validation rules and not all characters are supported literally in the predicate string. When the predicate is parsed, those characters may be interpreted as operators/structure (or may simply be disallowed), which would explain why escaping doesn’t help and why the action can’t be saved.

Use a supported matching pattern type

If the match predicate expects a specific pattern syntax (for example, glob-style or other limited wildcard pattern), stick to only the characters that syntax supports.

Rework the predicate to avoid disallowed characters

If ( ) ! aren’t allowed, you’ll likely need to express the matching logic using only supported wildcards (for example * / ? depending on what the predicate supports) and plain characters that are accepted.

Narrow the match using multiple simpler predicates (if your workflow supports it)

If you can’t match the whole expression in one predicate, consider splitting matching into multiple steps/conditions that each use only allowed characters

Verify whether special characters must be encoded

Some systems require a specific escaping/encoding approach, but since you already tried escaping “without success,” the most likely outcome is that these characters are either not escapable in that predicate syntax or are explicitly rejected by validation.

Please "upvote" if the information helped you. This will help us and others in the community as well.
Thomas Bolon 1 Reputation point

2026-06-16T14:46:18.9966667+00:00

Here is the page with the documentation: https://learn.microsoft.com/en-us/azure/storage-actions/storage-tasks/storage-task-conditions-operations-edit?tabs=azure-portal#use-a-wildcard-in-string-values

And another one: https://learn.microsoft.com/en-us/azure/storage-actions/storage-tasks/storage-task-conditions
Vallepu Venkateswarlu 10,590 Reputation points Microsoft External Staff Moderator

2026-06-16T16:23:18.54+00:00

Hi Thomas Bolon

Can you please share the requested details in private message for further troubleshoot.

Thomas Bolon 1

I am not sure to understand what are the requested details?

Here is the code returned in the "code" tab which does not work:

[[matches(Name, '((DEL!(???)))')]]

And here is the raw error returned when deploying the action:

{
  "code": "DeploymentFailed",
  "target": "/subscriptions/xxx/resourceGroups/xxx/providers/Microsoft.Resources/deployments/xxx_1781682896060",
  "message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.",
  "details": [
    {
      "code": "ValidationFailed",
      "message": "The value of the property 'Name' is '' and it does not follow the pattern '^.{1,1024}$'."
    }
  ]
}

Edit: I just saw the private message and replied.

Vallepu Venkateswarlu 10,590 Reputation points Microsoft External Staff Moderator

2026-06-17T08:52:04+00:00

Hi Thomas Bolon
Thank you for sharing the details. As I can see from your private message, you will be available next Tuesday. We will test the same scenario in our environment and connect with you on that day to discuss and troubleshoot the issue further.

In the meantime, we will continue our investigation and keep you updated on any findings.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-07-14T16:54:07.58+00:00

Hello @Thomas Bolon
Can you please update us if the action plan provided was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.

If these answer your question, click "Upvote" which may be beneficial to other community members reading this thread.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-07-15T17:36:54.8433333+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Thomas Bolon 1 Reputation point

2026-07-17T09:31:53.05+00:00

Hello @Snehitha Muduganti I did not receive any news from @Vallepu Venkateswarlu for a direct connection, I did not receive any email.
Praveen Kumar Gudipudi 2,295 Reputation points Microsoft External Staff Moderator

2026-07-28T12:19:04.7333333+00:00
Hello @Thomas Bolon ,

Could you please check the below suggested steps and let us know with an update.

Validate supported pattern syntax

Confirm that only '*' and '?' wildcards are used in match patterns. Do not rely on regex constructs or special characters. Re-test with a simple pattern to confirm: [[matches(Name, 'DEL???')]] should save successfully if syntax is correct.

Avoid disallowed characters in matches()

Remove parentheses and exclamation mark from the matches() pattern. For example, if possible: [[matches(Name, 'DEL')]] or [[matches(Name, 'DEL???')]].

If precision is required, proceed with the next step to compose conditions.

3.Break the logic into supported primitives

Combine simpler string functions that accept literal characters:

Use startsWith(), endsWith(), and/or contains() with the literal segments that include parentheses and '!' if the portal allows them in plain string literals (not as part of match patterns).

Example approach (if your UX allows):

startsWith(Name, '((DEL!') AND endsWith(Name, ')))')

Then use matches() only for the variable portion where wildcards are allowed (if necessary and the DSL supports combining with AND).

If the literal parentheses or '!' are rejected even in contains/startsWith/endsWith, proceed to step 4.

Use an alternative filtering strategy

If Storage Tasks cannot express this pattern precisely:

Loosen the match in Storage Tasks (e.g., a broader matches with '*' and '?') and perform precise filtering within the action’s downstream process (e.g., Azure Function or Logic App that checks the exact blob name).

Alternatively, drive the workflow via Event Grid subscription with additional filtering in a downstream function or app to handle the exact characters.

5.Re-test saving and deployment

After revising the condition, use the “Code” tab to verify the expression serializes correctly.

Deploy again and confirm no ARM validation errors occur.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-08-14T09:01:53.89+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-08-24T17:42:12.8533333+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Thomas Bolon 1 Reputation point

2026-09-02T19:34:03.55+00:00

We decided to not use Azure Storage Action because of this limitation, the query language is too limited for our use case and the other solution requires a workflow really too complex.

Our problem is that the pattern can occur anywhere inside the path, and there are variant with a ! or a X letter...

We decided to use the inventory tool and simply parse the CSV to detect such files with a standard .net program.

We did not try all alternatives suggested here, but at least the documentation should be updated to clearly indicate that some characters are not supported by the match function.

2 answers

Your answer

Thomas Bolon 1 Reputation point

2026-06-16T14:46:18.9966667+00:00

Here is the page with the documentation: https://learn.microsoft.com/en-us/azure/storage-actions/storage-tasks/storage-task-conditions-operations-edit?tabs=azure-portal#use-a-wildcard-in-string-values

And another one: https://learn.microsoft.com/en-us/azure/storage-actions/storage-tasks/storage-task-conditions
Vallepu Venkateswarlu 10,590 Reputation points Microsoft External Staff Moderator

2026-06-16T16:23:18.54+00:00

Hi Thomas Bolon

Can you please share the requested details in private message for further troubleshoot.
Thomas Bolon 1 Reputation point

2026-06-17T07:53:00.3366667+00:00

I am not sure to understand what are the requested details?

Here is the code returned in the "code" tab which does not work:

[[matches(Name, '((DEL!(???)))')]]

And here is the raw error returned when deploying the action:

{ "code": "DeploymentFailed", "target": "/subscriptions/xxx/resourceGroups/xxx/providers/Microsoft.Resources/deployments/xxx_1781682896060", "message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.", "details": [ { "code": "ValidationFailed", "message": "The value of the property 'Name' is '' and it does not follow the pattern '^.{1,1024}$'." } ] }

Edit: I just saw the private message and replied.
Vallepu Venkateswarlu 10,590 Reputation points Microsoft External Staff Moderator

2026-06-17T08:52:04+00:00

Hi Thomas Bolon
Thank you for sharing the details. As I can see from your private message, you will be available next Tuesday. We will test the same scenario in our environment and connect with you on that day to discuss and troubleshoot the issue further.

In the meantime, we will continue our investigation and keep you updated on any findings.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-07-14T16:54:07.58+00:00

Hello @Thomas Bolon
Can you please update us if the action plan provided was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.

If these answer your question, click "Upvote" which may be beneficial to other community members reading this thread.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-07-15T17:36:54.8433333+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Thomas Bolon 1 Reputation point

2026-07-17T09:31:53.05+00:00

Hello @Snehitha Muduganti I did not receive any news from @Vallepu Venkateswarlu for a direct connection, I did not receive any email.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-08-14T09:01:53.89+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Snehitha Muduganti 0 Reputation points Microsoft External Staff

2026-08-24T17:42:12.8533333+00:00

Hello @Thomas Bolon ,

Following up on previous communications, I wanted to confirm with you if you have any further questions or concerns about the issue reported or if you have the time to check the provided information.

Looking forward to your reply.
Thomas Bolon 1 Reputation point

2026-09-02T19:34:03.55+00:00

We decided to not use Azure Storage Action because of this limitation, the query language is too limited for our use case and the other solution requires a workflow really too complex.

Our problem is that the pattern can occur anywhere inside the path, and there are variant with a ! or a X letter...

We decided to use the inventory tool and simply parse the CSV to detect such files with a standard .net program.

We did not try all alternatives suggested here, but at least the documentation should be updated to clearly indicate that some characters are not supported by the match function.

Answer 1

This looks like a Storage Actions condition-serialization problem, not a Blob Storage filename restriction. In matches, only * and ? are wildcard characters. Parentheses and ! should be literal text.

If the three question marks are wildcards, your existing expression is valid in principle: [[matches(Name, '((DEL!(???)))')]].

If they are literal question marks, escape each one. In an ARM/Bicep/JSON string, the backslash also needs escaping, so the value becomes ((DEL!(\\?\\?\\?))).

The key clue is the deployment error saying Name is empty. That means the portal or resource provider is losing the value during validation, rather than rejecting the blob name itself.

As a workaround, build the condition from startsWith, contains, and endsWith clauses and use Preview Conditions before assigning the task. If the exact pattern still serializes as empty outside the portal, open an Azure support case and include the failed deployment operation ID and generated task JSON. This is likely a product defect.

Thomas Bolon 1 Reputation point

2026-09-02T19:35:24.59+00:00

We tried all kind of escaping, and there is definitively something wrong during the serialization. We decided to not rely on this tool because of these limitations.

Answer 2

Hello Thomas Bolon,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that your Azure Storage Action: can't use parenthesis or exclamation mark on blob name match predicate.

What you can do is:

If the blob name must match the exact literal value ((DEL!(???))), do not use matches(). Use equals(): [[equals(Name, '((DEL!(???)))')]]
If ??? is intended to mean exactly three variable characters, and the literal parentheses and ! must also be part of the match, Azure Storage Actions currently does not provide a documented reliable escape syntax for that full matches() expression. In that case, use a pre-classification step, such as Azure Function, Azure SDK, or automation job, to identify matching blobs and write a blob index tag or metadata value, then target that marker from Storage Actions using equals().

For an example tag-based Storage Actions condition:

[[equals(Tags.Value[StorageActionMatch], 'DEL')]]

If blob index tags are not suitable for the account type or namespace configuration, use metadata instead:

[[equals(Metadata.Value[StorageActionMatch], 'DEL')]]

After switching exact-name matching to equals(), the Storage Action condition avoids wildcard parsing and should save/deploy successfully. If the wildcard version is required and matches() still fails with parentheses or !, the next action should be a Microsoft support escalation against Azure Storage Actions condition parsing, because the current documentation does not provide a supported syntax to express that pattern safely.

For more reading and steps:

I hope this is helpful. Please! Do not hesitate to let me know if you have any other questions, steps or clarifications.

Please do not close the thread by upvoting and accepting the answer if any part of it is helpful.

Thomas Bolon 1 Reputation point

2026-09-02T19:36:57.4166667+00:00

??? is intended to match exactly 3 arbitrary digits, so yes, this is a limitation of the tool. We decided to not use this feature, and instead rely on a classic .net program.