[GH-ISSUE #354] Chroma Tags Json Template Not Sending Correct "if-modified-since" HTTP Header #3523

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sascha_hemi · 2026-03-20T23:06:25+01:00

sascha_hemi commented

2026-03-20 23:06:25 +01:00

Originally created by @LeftPinkie on GitHub (Jul 29, 2024).
Original GitHub issue: https://github.com/OpenEPaperLink/OpenEPaperLink/issues/354

Describe the bug
For Chroma sub GHz tags using "Json template" as content, the HTTP header "if-modified-since" is not sending correctly. It is sending "Thu, 01 Jan 1970 00:00:00 GMT". Forgive me and let me know if I should be posting this issue on "skiphansen/OpenEPaperLink" repo instead.

To Reproduce
Steps to reproduce the behavior:

Configure AP for sub GHZ.
Set the a Chroma tag for content of "Json template" and give it a remote URL.
On the remote host, capture the incoming request.
See error:

...
x-esl-mac: 4467090000033196
if-modified-since: Thu, 01 Jan 1970 00:00:00 GMT
...

Expected behavior
The HTTP header should have a valid date:

if-modified-since: Mon, 29 Jul 2024 00:06:10 GMT

Screenshots
n/a

Additional context
The AP's ./current/tagDB.json does have a valid "lastseen" timestamp.

AP...
env: OpenEPaperLink_Mini_AP_v4
build date: 2024-07-20 07:41
esp32 version: chroma_v0007

Tag...
skiphansen/OpenEPaperLink SubGhz Beta #7 chroma29_full_0007.bin

Originally created by @LeftPinkie on GitHub (Jul 29, 2024). Original GitHub issue: https://github.com/OpenEPaperLink/OpenEPaperLink/issues/354 **Describe the bug** For Chroma sub GHz tags using "Json template" as content, the HTTP header "if-modified-since" is not sending correctly. It is sending "Thu, 01 Jan 1970 00:00:00 GMT". Forgive me and let me know if I should be posting this issue on "skiphansen/OpenEPaperLink" repo instead. **To Reproduce** Steps to reproduce the behavior: 1. Configure AP for sub GHZ. 2. Set the a Chroma tag for content of "Json template" and give it a remote URL. 3. On the remote host, capture the incoming request. 4. See error: ``` ... x-esl-mac: 4467090000033196 if-modified-since: Thu, 01 Jan 1970 00:00:00 GMT ... ``` **Expected behavior** The HTTP header should have a valid date: ``` if-modified-since: Mon, 29 Jul 2024 00:06:10 GMT ``` **Screenshots** n/a **Additional context** The AP's `./current/tagDB.json` does have a valid "lastseen" timestamp. AP... env: OpenEPaperLink_Mini_AP_v4 build date: 2024-07-20 07:41 esp32 version: chroma_v0007 Tag... skiphansen/OpenEPaperLink SubGhz Beta #7 chroma29_full_0007.bin

sascha_hemi added the bug label 2026-03-20 23:06:25 +01:00

sascha_hemi closed this issue

2026-03-20 23:06:25 +01:00

sascha_hemi commented

2026-03-20 23:06:26 +01:00

@LeftPinkie commented on GitHub (Jul 30, 2024):

I figured out the "issue". If I pull up the tag's content config screen and save it, whether or not I made any changes, then the next request will send the "if-modified-since" header as 0 or Thu, 01 Jan 1970 00:00:00 GMT, regardless of what's in the tagDB. I guess this can be considered a feature in case the URL has changed and therefore it would be a brand new request.

@LeftPinkie commented on GitHub (Jul 30, 2024): I figured out the "issue". If I pull up the tag's content config screen and save it, whether or not I made any changes, then the next request will send the "if-modified-since" header as 0 or Thu, 01 Jan 1970 00:00:00 GMT, regardless of what's in the tagDB. I guess this can be considered a feature in case the URL has changed and therefore it would be a brand new request.

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Reference: starred/OpenEPaperLink#3523