InvalidTemplate. Unable to process template language expressions in action 'Get_Attachment_by_REST' inputs at line '1' and column '19622': 'The template language function 'base64ToString' was invoked with a parameter that is not valid. The value cannot be decoded from base64 representation.'.

[niranjanmankame]

Hi All,

Need help in resolving this Error

InvalidTemplate. Unable to process template language expressions in action 'Get_Attachment_by_REST' inputs at line '1' and column '19622': 'The template language function 'base64ToString' was invoked with a parameter that is not valid. The value cannot be decoded from base64 representation.'.

This is the node which is throwing the above error

Any help in resolving this is Highly Appreciated.

Regards,

Niranjan

[PrasadAthalye]

Can you check what is the format of VersionData from salesforce?

[v-litu-msft · Accepted solution]

Hi @niranjanmankame,

Casuse the Authorization request header contains the credentials to authenticate a user agent with a server and the format should be base64 code, so the access token should be valid that could be converted to base64.

You could check if the access token has any invalid character to base64:

Base64 - Wikipedia

And please make sure the single quotation marks appear in pairs:

Best Regards,
Community Support Team _ Lin Tu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[Polymer3]

@v-litu-msft I am having the same issue, could you provide some more info on how to solve.

If I understood what you were saying, the output/accesstoken being generated might not be in base64.

My output is the below - and I think the access_token has non base64 char (e.g. !)

What would be a solution to this? Can we just convert the token, but then it wouldn't work because it wouldn't be correct token.

Thanks

[jamiehandelman]

Did you ever find a solution to this? I am running into the same issue. Thanks!

[Polymer3]

@jamiehandelman unfortunately no.

I did actually get in touch with the guy who wrote the original article about this, but he couldn't help solve it

[AllenTheGreat]

FYI: I was running into this issue and could not find a solution online, but ended up working through and finding out the cause.

Base64 strings have to have a length that is divisible by 4, if the length is not divisible by 4, they append '=' as a placeholder on the end of the string until it is divisible by 4. Microsoft Flow's decodeBase64() does not automatically append these =, so you have to check if mod(length(variables('X')) == 0, if not, append '=' to the string until it is. Then you can decode the string.

[AllenTheGreat]

Please look at my post below for the solution.

[Polymer3]

Hi,

Thanks so much for this solution.

Are you able provide the full expression it looks like its cut off.

Also for the append.

(I am trying to do it to an array, if that makes a difference)

[RobotRising]

The full expression is: 

mod(length(variables('Base64')), 4) 

however, the Base64 encoded text inside of the url might already be divisible by 4 so you will need to also add a condition at the top that checks if  mod(length(variables('Base64')), 4) equals 0, if it does  then base64ToString(variables('Base64')) or decodebase64, if it does not then use a do until 

mod(length(variables('Base64')), 4) equals 0 and append an equals every time 

[JColvin]

@Polymer3 did you ever get this figured out? Like you, I received an access token from Salesforce that had non-base64 characters my Power Automate didn't like. Even if I account for the token length needing to be divisible by 4, this issue remains. How do I get an access token from Salesforce that doesn't include the invalid characters?

[Polymer3]

@JColvin I never did come back to it.

To confirm you saying that even with @RobotRising solution above (including the adding zeros) - it still doesn't work?

[JColvin]

@Polymer3 

After much pain and anguish, I found that the issue was the formatting of the URI in the HTTP action. If I formatted the HTTP action like this...

...I kept getting the "invalid template" error. But once I put the URI into a variable, it started working!

[Polymer3]

Is this with @RobotRising solution of adding zeros until /4 is possible